BIO-LPG PRODUCTION PROCESS

Abstract

The present invention is in the field of processes for the production of BioLPG, and catalysts for use in said processes.

Claims

1. A process for the selective production of BioLPG from C2 or C3 aliphatic alcohols, wherein the process comprises: (a) introducing a feedstream comprising one or more C2 or C3 aliphatic alcohols into a reaction vessel comprising a catalyst, wherein the catalyst comprises a ZSM5 zeolite material, an MCM22 zeolite material, or a combination thereof; (b) contacting the feedstream and catalyst within the reaction vessel at a temperature of from 250 C. to 750 C. and a pressure of from 0.5 atm to 50 atm; and (c) recovering a product stream comprising C3 and/or C4 aliphatic hydrocarbons from the reaction vessel.

2. A process according to claim 1, wherein the contacting is carried out at a temperature of from 350 C. to 600 C., and preferably from 375 C. to 500 C.

3. A process according to claim 1 or claim 2, wherein the contacting is carried out at a pressure of from 1 atm to 20 atm; preferably 1 atm to 15 atm; and more preferably 1 atm to 10 atm.

4. A process according to claim 1 or claim 2, wherein the contacting is carried out at a pressure of from 3 atm to 50 atm, preferably 3 atm to 20 atm, more preferably 3 atm to 15 atm, and most preferably from 3 atm to 10 atm.

5. A process according to any preceding claim, wherein process steps a) to c) are carried out continuously as a continuous flow process.

6. A process according to claim 5, wherein the continuous flow process comprises introducing the feedstream to the reactor vessel at a flow rate of from 1 L to 10 L per minute per 150 mg of catalyst present in the reactor vessel; preferably, at a flow rate of from 1 L to 7.5 L per minute per 150 mg of catalyst present in the reactor vessel; more preferably, at a flow rate of from 1 L to 5 L per minute per 150 mg of catalyst present in the reactor vessel.

7. A process according to claim 5 or claim 6, wherein the continuous flow process comprises introducing the feedstream to the reactor vessel at a flow rate of from 1 L to 3 L per minute per 150 mg of catalyst present in the reactor vessel, preferably, at a flow rate of from 1.5 L to 2.5 L per minute per 150 mg of catalyst present in the reactor vessel, and most preferably at a flow rate of from 1.75 L to 2.25 L per minute per 150 mg of catalyst present in the reactor vessel.

8. A process according to any of claims 5 to 7, wherein the process further comprises passing an inert gas such as argon through the reaction vessel during contacting step b), preferably wherein the inert gas is introduced into the reaction vessel at a flow rate of from 0.5 ml/min to 10 ml/min per 150 mg of catalyst, preferably 0.5 ml/min to 5 ml/min per 150 mg of catalyst, more preferably 1.5 ml/min to 5 ml/min per 150 mg of catalyst, and most preferably from 2 ml/min to 5 ml/min per 150 mg of catalyst.

9. A process according to any of claims 5 to 8, wherein the contacting is carried out at a pressure of from 1 atm to 20 atm; wherein the continuous flow process comprises introducing the feedstream to the reactor vessel at a flow rate of from 1 L to 3 L per minute per 150 mg of catalyst present in the reactor vessel; and wherein the process further comprises passing an inert gas such as argon through the reaction vessel during contacting step b), wherein the inert gas is introduced into the reaction vessel at a flow rate of from 0.5 ml/min to 5 ml/min per 150 mg of catalyst.

10. A process according to any preceding claim, wherein contacting step b) further comprises contacting the catalyst with an inert diluent gas, such as nitrogen.

11. A process according to any preceding claim, wherein prior to step a), the catalyst is contacted with air or oxygen at a temperature of from 400 C. to 650 C. for a time period of from 1 hour to 10 hours, preferably wherein the catalyst is contacted with air or oxygen at a temperature of from 500 C. to 600 C. for a time period of from 4 hours to 6 hours.

12. A process according to claim 11, wherein prior to step a), but after the catalyst has been contacted with air or oxygen at a temperature of from 400 C. to 650 C. for a time period of from 1 hour to 10 hours, the reaction vessel is heated to a temperature of from 400 C. to 500 C. under air or oxygen flow for a time period of from 5 hours to 10 hours, before purging with an inert gas such as argon.

13. A process according to any preceding claim, wherein the one or more C2 or C3 aliphatic alcohols comprise ethanol, isopropyl alcohol, or a combination thereof.

14. A process according to claim 13, wherein the one or more C2 or C3 aliphatic alcohols are derived from fermentation or bio-generation, such as derived from fermentation of flue gases or bio-generated syngas.

15. A process according to any preceding claim, wherein the feedstream comprising one or more C2 or C3 aliphatic alcohols comprises the one or more C2 or C3 aliphatic alcohols in an amount of from 70% by weight to 100% by weight, preferably from 80% to 100% by weight of the total weight of components of the feedstream.

16. A process according to claim 14 or claim 15, wherein the feedstream comprising one or more C2 or C3 aliphatic alcohols further comprises water.

17. A process according to claim 16, wherein the water is present in the feedstream in an amount of from 1% by weight to 30% by weight of the total weight of components of the feedstream.

18. A process according to claim 17, wherein the water is present in the feedstream in an amount of from 10% by weight to 20% by weight of the total weight of components of the feedstream.

19. A process according to claim 17 or claim 18, wherein the feedstream comprises ethanol in an amount of from 70% by weight to 99% by weight, and preferably from 80% by weight to 90% by weight of the total weight of components of the feedstream.

20. A process according to any one of claims 5 to 19, wherein the process has a selectivity for C3 and C4 aliphatic hydrocarbons after two days of at least 30%, when the flow rate of the feedstream is from 1.75 L to 2.25 L per minute per 150 mg of catalyst present in the reactor vessel.

21. A process according to any preceding claim, wherein the reaction vessel comprises a fixed bed reactor or a fluidised bed reactor.

22. A process according to any preceding claim, wherein the catalyst further comprises a carrier, binder, or support material.

23. A process according to any preceding claim, wherein the catalyst comprises a ZSM5 zeolite material, wherein the ZSM5 zeolite material has a Si/Al ratio of from 20 to 150, preferably wherein the Si/Al ratio is from 25 to 100, more preferably wherein the Si/Al ratio is from 25 to 90, and most preferably wherein the Si/Al ratio is 30 or 80.

24. A process according to any preceding claim, wherein the catalyst comprises MCM22 with a Si/Al ratio of from 10 to 70.

25. A process according to any preceding claim, wherein the ZSM5 zeolite material or the MCM22 zeolite material are promoted zeolite materials that have reduced acidity as determined by temperature programmed desorption of ammonia, relative to the corresponding unpromoted zeolite material with equivalent Si/Al ratio.

26. A process according to claim 25, wherein the ZSM5 zeolite material or the MCM22 zeolite material have one or both of: i) a different acid site strength distribution as determined by temperature programmed desorption of ammonia, as the corresponding unpromoted zeolite material with equivalent Si/Al ratio; and ii) a different total number of acid sites as determined by temperature programmed desorption of ammonia, as the corresponding unpromoted zeolite material with equivalent Si/Al ratio.

27. A process according to any preceding claim, wherein the ZSM5 zeolite material or the MCM22 zeolite material are promoted zeolite materials comprising one or more promoter elements selected from boron, phosphorus, gallium, magnesium, zinc, potassium and zirconium.

28. A process according to claim 27, wherein the one or more promoter elements are present in the zeolite material in an amount of from 0.5 wt % to 5 wt %, preferably from 0.75 wt % to 3.25 wt %.

29. A process according to any preceding claim, wherein the catalyst comprises a ZSM5 zeolite material, wherein the ZSM5 zeolite material comprises a promoted ZSM5 zeolite material promoted with the elements boron or phosphorus.

29. s according to claim 29, wherein the boron or phosphorus are present in the ZSM5 material in an amount of from 0.75% to 3.25% by weight, preferably from 1% to 3% by weight.

31. A process according to claim 29 or claim 30, wherein the ZSM5 zeolite material has a Si/Al ratio of from 25 to 90, and most preferably wherein the Si/Al ratio is 25 to 35 or 75 to 85.

32. A process according to claim 31, wherein the ZSM5 zeolite material has an Si/Al ratio of 75 to 85, and wherein the ZSM5-zeolite material comprises from 0.75% by weight phosphorus to 1.25% by weight phosphorus, preferably wherein the ZSM-5 zeolite material has an Si/Al ratio of 80 and wherein the ZSM5-zeolite material comprises 1% by weight phosphorus.

33. A process according to claim 31, wherein the ZSM5 zeolite material has an Si/Al ratio of 25 to 30, and wherein the ZSM5-zeolite material comprises from 0.75% by weight phosphorus to 3.25% by weight phosphorus, preferably wherein the ZSM-5 zeolite material has an Si/Al ratio of 30 and wherein the ZSM5-zeolite material comprises 1% by weight phosphorus, 2% by weight phosphorus, or 3% by weight phosphorus.

34. A process according to claim 31, wherein the ZSM5 zeolite material has an Si/Al ratio of 75 to 85, and wherein the ZSM5-zeolite material comprises from 0.75% by weight boron to 3.25% by weight boron, preferably wherein the ZSM-5 zeolite material has an Si/Al ratio of 80 and wherein the ZSM5-zeolite material comprises 1% by weight boron, 2% by weight boron, or 3% by weight boron.

35. A process according to claim 31, wherein the ZSM5 zeolite material has an Si/Al ratio of 25 to 35, and wherein the ZSM5-zeolite material comprises from 0.75% by weight boron to 3.25% by weight boron, preferably wherein the ZSM-5 zeolite material has an Si/Al ratio of 30 and wherein the ZSM5-zeolite material comprises 1% by weight boron, 2% by weight boron, or 3% by weight boron.

36. A process according to any one of claims 5 to 35, wherein the process further comprises stopping the continuous process of steps a) to c); and contacting the catalyst with air or oxygen under conditions sufficient to rejuvenate the catalyst.

37. A process according to any one of claims 5 to 36, wherein the process further comprises stopping the continuous process of steps a) to c); and contacting the catalyst with air or oxygen at a temperature of from 300 C. to 600 C. for a time period of from 1 hour to 20 hours, preferably wherein the catalyst is contacted with air or oxygen at a temperature of from 400 C. to 550 C. for a time period of from 5 hours to 15 hours.

38. A process according to claim 36 or claim 37, wherein the catalyst is rejuvenated such that the catalyst has an activity and selectivity equivalent to an initial activity and selectivity of the catalyst.

39. A process according to claim 36 or claim 37, wherein the catalyst is rejuvenated such that the catalyst has an activity and selectivity equivalent to 70% or more, 80% or more, or 90% or more of an initial activity and selectivity of the catalyst.

40. A process for the selective production of BioLPG from C2 or C3 aliphatic alcohols, wherein the process comprises: (a) introducing a feedstream comprising one or more C2 or C3 aliphatic alcohols into a reaction vessel comprising a catalyst, wherein the catalyst comprises a ZSM5 zeolite material, an MCM22 zeolite material, or a combination thereof; (b) contacting the feedstream and catalyst within the reaction vessel at a temperature of from 250 C. to 750 C.; and (c) recovering a product stream comprising C3 and/or C4 aliphatic hydrocarbons from the reaction vessel; wherein the process is a continuous flow process, and wherein the process comprises introducing the feedstream to the reactor vessel at a flow rate of from 1 L to 10 L per minute per 150 mg of catalyst present in the reactor vessel, and wherein the process further comprises passing an inert gas such as argon through the reaction vessel during contacting step b), wherein the inert gas is introduced into the reaction vessel at a flow rate of from 0.5 ml/min per 150 mg of catalyst to 10 ml/min per 150 mg of catalyst, preferably 0.5 ml/min per 150 mg of catalyst to 5 ml/min per 150 mg of catalyst, more preferably 1.5 ml/min to 5 ml/min, per 150 ml of catalyst and most preferably from 2 ml/min to 5 ml/min per 150 mg of catalyst.

41. A process according to claim 40, wherein the process is as further defined as in any one or more of claims 1 to 39.

42. A catalyst comprising a ZSM5 zeolite material, an MCM22 zeolite material, or a combination thereof, wherein the ZSM5 zeolite material has a Si/Al ratio of from 20 to 150, and wherein the MCM22 zeolite material has a Si/Al ratio of from 10 to 70, and wherein the ZSM5 zeolite material or the MCM22 zeolite material are promoted zeolite materials that have reduced acidity as determined by temperature programmed desorption of ammonia, relative to the corresponding unpromoted zeolite material with equivalent Si/Al ratio.

43. A catalyst according to claim 42, wherein the catalyst is as further defined in any one of claims 22 to 35.

44. Use of a catalyst according to claim 42 or claim 43 for the conversion of C2 or C3 aliphatic alcohols to C3 and/or C4 aliphatic hydrocarbons.

45. Use according to claim 44, wherein the use further comprises the use of the catalyst in a process according to any one of claims 1 to 41.

46. Use according to claim 44 or claim 45, wherein the use comprises producing the C3 and/or C4 aliphatic hydrocarbons with a yield of at least 30%, preferably at least 40%, and most preferably at least 50%.

47. A process for rejuvenating a deactivated BioLPG production catalyst comprising a ZSM5 zeolite material or an MCM22 zeolite material, wherein the method comprises contacting the catalyst with air or oxygen, preferably wherein the method comprises contacting the catalyst with air or oxygen at a temperature of from 300 C. to 600 C. for a time period of from 1 hour to 20 hours, preferably wherein the catalyst is contacted with air or oxygen at a temperature of from 400 C. to 550 C. for a time period of from 5 hours to 15 hours.

48. A process according to claim 47, wherein the catalyst is rejuvenated such that the catalyst has an activity and selectivity equivalent to an initial activity and selectivity of the catalyst.

49. A process according to claim 47 or claim 48, wherein the catalyst is as defined in any one of claims 22 to 35.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] FIG. 1 shows the product selectivity of a process of the invention conducted using a 100 mg of a ZSM5 zeolite catalyst.

[0093] FIG. 2 shows the product selectivity of a process of the invention conducted using a 200 mg of a ZSM5 zeolite catalyst.

[0094] FIG. 3 shows the product selectivity of a process of the invention using 100 mg of zeolite catalyst MCM22.

[0095] FIG. 4 shows the product selectivity of a process for converting ethanol into hydrocarbons using 100 mg of zeolite catalyst SAPO34.

[0096] FIGS. 5 & 6 show the product selectivity for C3/C4 hydrocarbons of different zeolite catalysts in processes of converting ethanol into hydrocarbons.

[0097] FIG. 7 shows the product selectivity of a process of converting ethene into hydrocarbons using ZSM5 as the catalyst.

[0098] FIGS. 8 to 16 show the product selectivity of processes of the invention where the processes are carried out for different time periods, with differing amounts of catalyst.

[0099] FIG. 17 shows the product selectivity of a process of the invention conducted using a boron promoted ZSM5 zeolite catalyst.

[0100] FIG. 18 shows the product selectivity of a process of the invention conducted using a phosphorus promoted ZSM5 zeolite catalyst.

[0101] FIG. 19 contrasts the processes shown in FIGS. 17 and 18.

[0102] FIG. 20 shows the product selectivity of a process of the invention conducted using a ZSM5-30 catalyst.

[0103] FIG. 21 shows the product selectivity of a process of the invention conducted using a ZSM5-80 catalyst.

[0104] FIG. 22 shows the gas chromatography spectrum of the products of a process of the invention performed with a phosphorus promoted ZSM5-30 catalyst.

[0105] FIG. 23 shows the product selectivity of a process for converting ethanol into hydrocarbons using a zirconium promoted ZSM5-30 catalyst.

[0106] FIG. 24 shows the product selectivity of a process for converting ethanol into hydrocarbons using a vanadium promoted ZSM5-30 catalyst.

[0107] FIGS. 25 to 28 show the product selectivities of catalysts of the invention in processes of the invention where the feedstream comprises a mixture of water and ethanol.

[0108] FIGS. 29 to 35 show the product selectivities of various phosphorus and boron promoted catalysts of the invention when used in various processes of the invention.

[0109] FIGS. 36 to 39 show the product selectivities of various processes of the invention with pure anhydrous ethanol feedstreams and feedstreams comprising mixtures of ethanol and water.

[0110] FIGS. 40 to 43 show the product selectivities of various processes of the invention with pure isopropanol feedstreams and feedstreams comprising isopropanol and ethanol mixtures.

[0111] FIGS. 44 to 46 show the ammonia temperature programmed desorption (NH3 TPD) spectra of various zeolite catalysts.

[0112] FIGS. 47 and 48 show porosity data for various zeolite catalysts.

[0113] FIGS. 49 to 54 show the linear isotherm plots for various zeolite catalysts.

[0114] FIGS. 55 to 62 show general trends in selectivity for tested catalysts at different operating conditions.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

[0115] Testing was performed with the commercially available zeolites ZSM5, MCM22 and SAPO34. The one or more C2 or C3 aliphatic alcohols used as a feedstream for the process comprised ethanol.

[0116] Reaction vessels were loaded with the amounts of catalyst and silicon carbide shown in Table 1.

TABLE-US-00001 TABLE 1 Reaction Vessel Catalyst Mass of catalyst (mg) Mass of SiC (mg) 1 Blank 0 500 2 ZSM5 100 200 3 MCM22 100 0 4 SAPO34 200 0 5 SAPO34 100 100 6 ZSM5 200 100

[0117] Prior to loading in the reaction vessels, all zeolites were exposed to air at 550 C. for 5 hours to make sure they were in the H-form. After loading of the reaction vessels, the reaction vessels were heated under air flow (25 ml/min/block of eight tubes) to 460 C., and held for 7 hours. The tubes were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. Ethanol was then introduced to each reaction vessel at a rate of 2.5 L/min at a temperature of 400 C. Argon was introduced at a rate of 0.625 ml/min per reaction vessel tube as the internal standard and nitrogen was introduced to each catalyst bed in each reaction vessel at a rate of 37.5 ml/min per reaction vessel tube as a diluent gas. The purpose of the nitrogen diluent gas is simply to increase the space velocity for subsequent gas chromatography analysis.

[0118] The selectivity of each catalyst over time for formation of hydrocarbons of different chain length and diethyl ether are shown in FIGS. 1 to 7. FIG. 8 contrasts the selectivity over time for C3 and C4 aliphatic hydrocarbon formation of the different zeolites. FIG. 8 shows that the initial selectivity of the ZSM5 and MCM22 catalysts for C3 and C4 aliphatic hydrocarbon formation is significantly greater than the other zeolites. It can also be seen from FIG. 8 that after a short time period, the selectivity of all catalyst for formation of C3 and C4 aliphatic hydrocarbons decreases. However, this decrease in selectivity is significantly less for MCM22 and ZSM5 than it is for the other zeolites.

[0119] In all cases, very high ethanol to hydrocarbon product conversions were obtained of roughly 100%. For zeolite SAPO3, almost all ethanol was converted to ethylene and almost no other hydrocarbons were produced after several hours of running the reaction.

[0120] ZSM5 had a selectivity for C3 and C4 aliphatic hydrocarbons of around 55% to 60%. MCM22 had a selectivity for C3 and C4 aliphatic hydrocarbons of around 45% to 55%.

[0121] A similar experiment was carried out using ethene as a feedstream instead of ethanol. The results of this experiment with the different catalysts are shown in FIG. 9. It can be seen from FIG. 9 that the selectivities and lifetime for each catalyst are different when ethene is used as a feedstock instead of ethanol (as shown in FIG. 8). When using ethene as a feed, the zeolites suffered from much faster activation than when using ethanol as a feed. It can also be seen that C3/C4 (i.e. LPG) yields are higher when ethanol is used as a feed for the process than when ethene is used as a feed, for the MCM22 and ZSM5 zeolite catalysts.

Example 2

[0122] A similar experiment to Example 1 was carried out using only MCM22 and ZSM5 as catalysts, but investigating the effects of having the process online as a continuous process for a longer period of time.

[0123] Reaction vessels were loaded with the amounts of catalyst and silicon carbide shown in Table 2.

TABLE-US-00002 TABLE 2 Reaction Vessel Catalyst Mass (mg) SiC (mg) 1 Blank 0 500 2 ZSM5 150 150 3 ZSM5 100 200 4 ZSM5 50 300 5 ZSM5 25 300 6 MCM22 150 0 7 MCM22 100 50 8 MCM22 50 100

[0124] Prior to loading in the reaction vessels, all zeolites were exposed to air at 550 C. for 5 hours to make sure they were in the H-form. After loading of the reaction vessels, the reaction vessels were heated under air flow (35 ml/min/block of eight tubes) to 470 C., and held for 7 hours. The tubes were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. Ethanol was then introduced to each reaction vessel at a rate of 2.5 L/min at a temperature of 400 C. Argon was introduced at a rate of 0.625 ml/min per reaction vessel tube as the internal standard and nitrogen was introduced to each catalyst bed in each reaction vessel at a rate of 37.5 ml/min per reaction vessel tube as a diluent gas. The temperature was increased to 425 C. after the reaction had been online for 11 days. The purpose of the nitrogen diluent gas is simply to increase the space velocity for subsequent gas chromatography analysis.

[0125] In this experiment, different catalysts loadings were used to try and determine total ethanol conversion per gram of catalyst.

[0126] It was also investigated whether in situ rejuvenation of the catalysts could be achieved, which would extend the overall lifetimes of the catalysts. Accordingly, a first rejuvenation of the catalysts were carried out after 4 days online followed by another 4 days of catalysis prior to a second rejuvenation followed by a further 5 days of catalysis.

[0127] The results of the experiments are shown in FIGS. 10 to 18.

[0128] FIG. 10 shows that the initial selectivity for C3 and C4 hydrocarbons with ZSM5 is high at roughly 55% to 65%. It was also found that for the first 24 hours online the main fraction was C3 but that this ratio changes in favour of C4 compounds after 1 day online. FIG. 11 shows that the selectivity for C3 and C4 hydrocarbons gradually drops after several days online.

[0129] The data in FIGS. 11 to 14 which contrasts different loadings of ZSM5 catalyst shows the start of catalyst deactivation at different times online. This is indicative that catalyst deactivation is more affected by the total ethanol concentration than the time online. An indicator of catalyst deactivation is the sudden increase of C2 hydrocarbons as the zeolite starts to struggle to convert the C2 hydrocarbons to C3 and C4 hydrocarbons. If the appearance of C2 hydrocarbons is taken as the start of significant deactivation of the catalyst, then the data in Table 3 shows that ZSM5 deactivation starts after around 100 ml of ethanol has been converted per gram of ZSM5.

TABLE-US-00003 TABLE 3 Total ethanol Time online of delivered (ml) at ethene concentration flow rate of Total ml ethanol ZSM5 occurrence (hours) 2.5 L/min per gram of ZSM5 25 mg 18 2700 L 108 ml/g 50 mg 35 5250 L 105 ml/g 100 mg 62 9375 L 94 ml/g

[0130] The data in FIGS. 11 to 14 also shows significant deactivation of ZSM5 for the experiments performed at lower catalyst loadings. However, in situ air rejuvenation at 470 C. afforded near complete recovery of ZSM5 activity and selectivity. In some cases (for example, in the data shown in FIG. 12), the first rejuvenation actually improved the activity and selectivity of the catalyst over the initial activity and selectivity. Similar rejuvenation of activity and selectivity was achieved after the second air rejuvenation.

[0131] FIG. 15 shows that MCM22 shows a selectivity for C3 and C4 hydrocarbons over the first 24 hours online of about 45% to 55%. However after around 1 day online, the MCM22 catalyst starts to deactivate, as is shown by the increase in C2 hydrocarbon production. A similar comparison of the MCM22 data as done for the ZSM5 data discussed above shows that MCM22 deactivation starts after a total ethanol conversion of roughly 33 ml per gram of MCM22. However, advantageously, at all catalyst loadings, ethanol conversion was roughly 100%.

[0132] The deactivation of MCM22 was more marked than that of ZSM5 as ethene started to dominate after a shorter period online. Fortunately, once again an in-situ air rejuvenation at 470 C. afforded almost complete recovery of the MCM22 activity and selectivity. Furthermore, a similar recovery of activity and selectivity was observed after the second air rejuvenation. It was also noticeable that the MCM22 performance in terms of catalyst lifetime improved noticeably after the first and second rejuvenation relative to the fresh catalyst.

[0133] FIG. 18 compares the C3 and C4 selectivity of ZSM5 and MCM22. The data in the graph clearly shows the superior performance of ZSM5 in terms of both C3/C4 selectivity and catalyst stability.

Example 3

[0134] In this experiment, it was decided to investigate the effects of including promoter elements in the zeolite catalysts on the catalytic activity and selectivity of the catalysts, as well as on the lifetime of the catalysts.

[0135] The catalyst chosen for modification with promoter elements was ZSM5-30 (ZSM5 with a Si/Al ratio of 30). This zeolite is commercially available from Alfa Aesar as the ammonium salt. The catalyst was modified with the promoter elements boron and phosphorus. The compounds B1/ZSM5-30 and P1/ZSM5-30 were synthesised. The number specified in the formula after the promoter element (for example, B1) denotes the weight percentage at which the promoter element is included in the compound.

[0136] The compounds were synthesised using methods described in the literature, such as in Wang et al., Ind. Eng. Chem. Res., 2009, 48, 10788-10795.

[0137] Firstly, the ammonium salts were converted to their H-form by calcination at 550 C. for 5 hours. The incipient wetness point (IW) of the H-ZSM5(30) was measured at 0.852 g/g with water.

Synthesis of B1/ZSM5-30

[0138] Boric acid (0.29 g) was dissolved in 4 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to H-ZSM5 (30) with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

Synthesis of P1/ZSM5-30

[0139] Ammonium Phosphate dibasic (0.206 g) was dissolved in 4 mL of deionised water (incipient wetness, IW quantity) and added to the H-ZSM5 (30) slowly with agitation until all the liquid had been adsorbed and a paste was obtained. The material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

Testing of Catalytic Activity of Modified Zeolites

[0140] The catalytic activity of the boron and phosphorus modified ZSM5-30 catalysts was tested. The catalytic activity of unpromoted ZSM5-30 was tested, along with the catalytic activity of an unpromoted ZSM5-80 (Si/Al ratio=80) catalyst.

[0141] 150 mg of each catalyst was mixed with 150 mg of silicon carbide, before being loaded into reaction vessel tubes.

[0142] After loading into the reaction vessel tubes, the tubes were heated under air flow to 475 C., and held for 3 hours. The tubes were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. Ethanol was then introduced to each reaction vessel at a rate of 2.0 L/min at a temperature of 400 C. Argon was introduced at a rate of 0.625 ml/min per reaction vessel tube as the internal standard and nitrogen was introduced to each catalyst bed in each reaction vessel at a rate of 37.5 ml/min per reaction vessel tube as a diluent gas. These reaction conditions were maintained for the duration of the experiment. The purpose of the nitrogen diluent gas is simply to increase the space velocity for subsequent gas chromatography analysis.

[0143] The results of the experiment for the boron and phosphorus promoted catalysts are shown in FIGS. 19 and 20. FIG. 21 shows a comparison of the results of unpromoted ZSM5-30 with those of B1/ZSM5-30 and P1/ZSM5-30. It can be seen in FIG. 21 that both the promoted catalysts B1/ZSM5-30 and P1/ZSM5-30 had higher selectivity for C3 and C4 hydrocarbons than the unpromoted ZSM5-30 material. Additionally, both promoted catalysts had longer catalyst lifetimes than the corresponding unpromoted material. Whilst the initial selectivity of the phosphorus promoted catalyst was higher than the boron promoted catalyst, the extension of the lifetime of the boron promoted catalyst was greater. The lifetime extension of the catalyst is very significant in zeolite chemistry, and significantly improves the efficiency of the process. FIGS. 22 and 23 show the results of unpromoted HZSM5-30 and HZSM5-80. The HZSM5-80 catalyst has increased C3/C4 hydrocarbon selectivity, and also longer catalyst lifetime (shown by decreasing C3/C4 selectivity and increased C2 hydrocarbon production). FIG. 24 shows the gas chromatography spectrum of the products after 3 hours online for the P1/ZSM5-30 catalyst. It can be seen that C3 and C4 hydrocarbon compounds dominate the product spectrum with large peaks corresponding to propane, butane and isobutene.

Ammonia Programmed Desorption Spectra

[0144] Ammonia temperature programmed desorption (NH.sub.3-TPD) experiments were carried out on the zeolites to determine how the introduction of promoter elements into the zeolites affected their acidity properties.

Experimental Protocol

[0145] NH3-TPD experiments were carried out in a Micromeritics 2920, which is equipped with a TCD detector coupled to a Pfeiffer ThermoStar quadrupole mass spectrometer which allows the analysis and monitoring of gaseous products as a function of time or sample temperature.

[0146] Around 80 mg of sample was loaded into the U-shaped tube and attached to the instrument. The sample was dried under a flow of argon in a two-step process, at 120 C. for 30min and 500 C. for 20 min. Then, the sample is cooled down to 100 C. and saturated with NH3 by flowing 5% NH3/He for 1 h at this temperature, followed by an evacuation step lasting 1 h. The sample is then heated up to 500 C. to desorb NH3, with both TCD and MS monitoring the effluent gas during the desorption step.

[0147] The ions m/z 18, 17 and 14 were followed to monitor H2O.sup.+, OH.sup.+ and NH3.sup.+ and N+ ions profiles.

[0148] The data in Table 4 shows the total ammonia desorption values for the zeolites. The lower the total ammonia desorption value, the lower the acid site density of the zeolite. The acid site density is correlated to the total acidity of the zeolite (although it is not the sole determinant thereof). It can be seen that both the boron and phosphorus promoted zeolites both exhibited reduced acid site density compared to the unpromoted zeolite catalyst. This reduced acid site density is indicated by the lower values for total ammonia desorption. An analysis of the TPD spectrum of the zeolites also showed that the acid site distribution had shifted in the promoted zeolites such that the promoted zeolites had a higher ratio of weak acid sites to strong acid sites than the corresponding unpromoted zeolite material. This finding, in combination with the reduced acid site density, concludes that the promoted zeolite materials had a reduced acidity compared to the corresponding unpromoted zeolite material.

TABLE-US-00004 TABLE 4 Desorption lower Desorption higher Total temperature m/z17 temperature m/z17 Desorption m/z Norm. Area Norm. Area Norm. Area Sample (1010) (1010) (1010) H-ZSM5-30 2.59 2.05 4.64 B1ZSM5-30 4.24 P1ZSM5-30 2.10 1.46 3.56

[0149] It is believed by the inventors of the present invention that the increased selectivity of the promoted catalysts for C3 and C4 hydrocarbons is due, at least in part, to the reduced acidity of the promoted zeolite catalysts compared to the baseline corresponding unpromoted catalyst materials. To further investigate this, analysis of the porosity and pore structure of the catalysts was undertaken, and is described in further detail below.

Porosity Measurements

[0150] The porosity of all zeolite catalyst samples was measured on a Micromeritics Gemini VI instrument. With the surface area being calculated using the Brunauer, Emmett and Teller (BET) transformation. The Pore volume and area distribution are calculated using the Barret, Joyner and Helnda (BJH) method. The measurements are shown in Table 5 below. All samples show a very similar isotherm typical of ZSM5 zeolites with a hysteresis loop confirming type-IV behaviour. A number of features can be observed from the data collected. The ZSM5(80) has a higher surface area than the ZSM5(30) which is consistent with the manufacturers data and upon calcination of NH4-ZSM5(30) and removal of the ammonium counteranion the surface area is increased as would be expected.

TABLE-US-00005 TABLE 5 BET Surface Area Pore Volume Pore Size Sample (m2/g) (cm3/g) (Angstroms) NH.sub.4 ZSM5-80 516 0.30 34 NH.sub.4 ZSM5-30 370 0.22 39 H ZSM5-30 393 0.24 35 B1 ZSM5-30 332 0.21 42 P1 ZSM5-30 312 0.19 36

[0151] The addition of modifiers to the zeolites resulted in the surface area and pore volumes dropping slightly, however there are no large changes indicating that there is no pore blocking or significant structural changes in the material caused by the reaction conditions or ion exchange of the ammonium. This is also confirmed by the consistent nature of the isotherm for all samples showing the same underlying structure upon modification.

[0152] Without being limited by theory, the lack of significant change in pore structure of the zeolite catalysts upon promotion indicates it is likely that the changes in catalytic performance are primarily due to the reduction of the acid strength of the catalysts, as opposed to surface or structural properties of the catalyst.

[0153] To further investigate the effect of reducing the acidity of the zeolite catalysts, the promoted zeolite catalysts Zr1 ZSM5-30 and V ZSM5-30 were synthesised (ZSM5 promoted with 1 weight % zirconium and vanadium respectively). The total desorption (m/z 17 Norm. Area (10-10) of these catalysts was 4.72 and 5.69 respectively. The catalysts thus had a higher acid site density than the corresponding unpromoted zeolite catalyst which had a total desorption of 4.64 as shown above in Table 4. These catalysts did not show the improved C3/C4 hydrocarbon selectivity or improved catalyst lifetime associated with the boron and phosphorus promoted catalysts, as can be seen from a comparison of FIGS. 25 and 26 with FIGS. 22, 23 and 24.

Example 4

[0154] Example 4 was undertaken to investigate the effect on the process of using an ethanol feedstream with water vapour present therein. The feedstream used comprised around 12% water and around 88% ethanol.

[0155] The catalysts shown in Table 6 were tested.

TABLE-US-00006 TABLE 6 Sample Catalysts Mass (mg) SiC (mg) 1 Blank ethanol/H.sub.2O 0 500 2 ZSM5-30 150 150 3 ZSM5-80 150 150 4 B1/ZSM5-30 150 150 5 P1/ZSM5-30 150 150

Reaction Conditions

[0156] Each catalyst was placed in a separate reaction vessel. After loading the each reaction vessel with catalyst, the reaction vessels were heated under air flow to 475 C. and held for 3 hours. The reaction vessels were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. An ethanol/water mixture (88:12) (2.0 L/min/reaction vessel) was introduced at 400 C. and Argon (8 ml/min) was used as internal standard.

[0157] The results of these experiments are shown in FIGS. 27 to 30. The arrows displayed in these graphs indicate the time period after which the catalysts start deactivating when anhydrous ethanol is used. It can be seen from the graphs that none of the catalysts deactivate in the time period tested when 12% water is included in the feedstream, and that catalyst lifetime far exceeds that when anhydrous ethanol is used as the feedstream. When the process was stopped after nine days online, not one of the catalysts showed deactivation. The phosphorus promoted catalyst showed notably better C3 and C3/C4 selectivity when compared to the corresponding unpromoted zeolite material.

Example 5

[0158] A further study was undertaken to investigate the effects of including different levels of promoter elements in the zeolites.

[0159] The following catalysts were synthesised for testing: B1/ZSM5-30; B3/ZSM5-30; B1/ZSM5-80; B3/ZSM5-80; P1/ZSM5-30; P3/ZSM5-30; P1/ZSM5-80; and P3/ZSM5-80; P1/ZSM5-200; P2/ZSM5-30; P2/ZSM5-80; B1/ZSM5-200 and P1/ZSM5-200.

[0160] The Si/Al ratio of ZSM5-30, ZSM5-80 and ZSM5-200 is 30, 80 and 200 respectively.

[0161] The number specified in the formula after the promoter element corresponds to the weight percentage of the promoter element in the zeolite material.

Synthesis of Zeolites

[0162] The ZSM5 zeolites were obtained from Alfa Aesar.

[0163] The compounds were synthesised using methods described in the literature, such as in Wang et al., Ind. Eng. Chem. Res., 2009, 48, 10788-10795.

[0164] The zeolites used in the following procedures were in the protonated rather than the ammonium form, i.e. H-ZSM-5 and not NH4-ZSM-5. H-ZSM-5 materials were prepared by air calcination of the parent NH4-ZSM-5 zeolite at 550 C. for 5 hours. The incipient wetness points (IW) for the materials were measured in order that the incipient wetness impregnations can be carried out effectively.

Boron Promoted Zeolites

[0165] Modification with Boron is carried out using Boric acid which has a limited solubility of 5.7 g/100 mL. This required the 3% B to be prepared by multiple impregnations as opposed to a single impregnation.

B1/ZSM5-30

[0166]

TABLE-US-00007 H-ZSM5(30) 5 g H3BO3 290 mg

[0167] Boric acid (0.29 g) was dissolved in 4 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to H-ZSM5 (30) with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

B3/ZSM5-30

[0168]

TABLE-US-00008 B1/ZSM5-30 2.5 g H3BO3 145 mg

[0169] Boric acid (0.145 g) was dissolved in 2 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to the 1% boron promoted catalyst with manual mixing followed by drying in the fume cupboard, dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours. This calcined material was then subjected to the same procedure of Boron addition drying and calcination to produce the 3% boron on H-ZSM-5 (30).

B1/ZSM5-80

[0170]

TABLE-US-00009 H-ZSM5(80) 5 g H3BO3 290 mg

[0171] Boric acid (0.29 g) was dissolved in 4 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to H-ZSM5 (80) with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

B3/ZSM5-80

[0172]

TABLE-US-00010 B1/ZSM5-30 2.5 g H3BO3 145 mg

[0173] Boric acid (0.145 g) was dissolved in mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to the 1 weight % boron promoted catalyst with manual mixing followed by drying in the fume cupboard, dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours. This calcined material was then subjected to the same procedure of Boron addition drying and calcination to produce the 3% boron on H-ZSM-5 (80).

B1/ZSM5-200

[0174] Due to the limited pore volume of ZSM5-200 and the low solubility of boric acid the 1 wt % boron on ZSM5-200 was achieved by a double impregnation.

TABLE-US-00011 ZSM5-200 2.5 g H3BO3 73 mg

[0175] Boric acid (0.073 g) was dissolved in 1 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-200 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours. This calcined material was then subjected to the same procedure of Boron addition drying and calcination to produce the 1% boron on ZSM5-200.

Phosphorus Promoted Zeolites

[0176] Ammonium dihydrogen phosphate was used to modify the zeolites in this section, as the solubility of this material is 40 g/L at 25 C. the 3 wt % materials were produced in a single impregnation.

P1/ZSM5-30

[0177]

TABLE-US-00012 H-ZSM5-30 5 g (NH4)H2PO4 179 mg

[0178] Ammonium dihydrogen phosphate (0.179 g) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-30 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

P3/ZSM5-30

[0179]

TABLE-US-00013 H-ZSM5-30 5 g (NH.sub.4)H.sub.2PO.sub.4 555 mg

[0180] Ammonium dihydrogen phosphate (0.555 g) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-30 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

P1/ZSM5-80

[0181]

TABLE-US-00014 H-ZSM5-80 5 g (NH4)H2PO4 179 mg

[0182] Ammonium dihydrogen phosphate (0.179 g) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-80 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

P3/ZSM5-80

[0183]

TABLE-US-00015 H-ZSM5-80 5 g (NH.sub.4)H.sub.2PO.sub.4 555 mg

[0184] Ammonium dihydrogen phosphate (0.555 g) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-80 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

P1/ZSM5-200

[0185]

TABLE-US-00016 H-ZSM5-200 5 g (NH.sub.4)H.sub.2PO.sub.4 179 mg

[0186] Ammonium dihydrogen phosphate (0.179 g) was dissolved in 2 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-200 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

[0187] The following two materials in this study were prepared from Phosphoric acid (85%) and the amounts needed to yield 2 wt % P calculated from the properties of the acid.

P2/ZSM5-30

[0188]

TABLE-US-00017 H-ZSM5-30 5 g H.sub.3PO.sub.4 (85%) 0.223 mL

[0189] Phosphoric acid (0.223 mL) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-30 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

P2/ZSM5-80

[0190]

TABLE-US-00018 H-ZSM5-30 5 g H.sub.3PO.sub.4 (85%) 0.223 mL

[0191] Phosphoric acid (0.223 mL) was dissolved in 3 mL of deionised water (IW quantity) and warmed to 25 C. to ensure complete dissolution. This was added dropwise to ZSM5-30 with agitation, after complete addition of the solution the material was at the IW point, the material was left at room temperature for 1 hour then dried at 120 C. in air overnight followed by calcination at 550 C. for 4 hours.

Catalyst testing experiments

[0192] Certain catalysts were tested by being loaded into separate reaction vessels. Each reaction vessel comprised 150 mg of catalyst and 150 mg of silicon carbide.

Reaction Conditions

[0193] After loading into the reaction vessel tubes, the tubes were heated under air flow to 475 C., and held for 3 hours. The tubes were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. Ethanol was then introduced to each reaction vessel at a rate of 2.0 L/min at a temperature of 400 C. Argon was introduced at a rate of 1 ml/min per reaction vessel tube as the internal standard and nitrogen was introduced to each catalyst bed in each reaction vessel at a rate of 37.5 ml/min per reaction vessel tube as a diluent gas. These reaction conditions were maintained for the duration of the experiment. The purpose of the nitrogen diluent gas is simply to increase the space velocity for subsequent gas chromatography analysis.

[0194] The results for the boron promoted zeolites are shown in FIG. 31. It can be seen that all boron promoted catalysts showed good initial selectivity for C3/C4 hydrocarbons. All boron promoted catalysts demonstrated increased catalyst lifetime when compared to the corresponding baseline unpromoted catalyst ZSM5-30, with the exception of the catalyst B1-ZSM5-200. All boron promoted catalysts showed similar initial selectivity for C3/C4 hydrocarbons as the unpromoted ZSM5-30 catalyst, with the exception of B1ZSM5-200.

[0195] The results for the phosphorus promoted catalysts are shown in FIGS. 32 to 35. All of these phosphorus promoted catalysts had a higher initial C3/C4 selectivity than the unpromoted ZSM5-30. All of the phosphorus promoted catalysts showed a longer catalyst lifetime compared to unpromoted zeolite ZSM5-30. The catalysts with the longest lifetimes were P3ZSM5-30 and P1ZSM5-80. In particular, P1ZSM5-80 showed no signs of deactivation after 7 days online.

Example 6

[0196] Further testing was performed upon the catalysts P1ZSM5-30, P1ZSM5-80 and B1ZSM5-80 synthesised in Example 5, and ZSM5-30, using the same reaction conditions as specified in Example 5. The results of these tests are shown in FIGS. 36 and 37.

[0197] It can be seen that both promoted ZSM5-80 catalysts had a similar initial C3/C4 and C3 selectivities to unpromoted ZSM5-30. However, P1ZSM5-30 had a higher initial C3/C4 and C3 selectivity than all other catalysts. However, the P1ZSM5-30 catalyst deactivated the fastest out of all of the catalysts.

Example 6

[0198] A further experiment was undertaken to investigate using the promoted zeolite catalyst in processes of the invention where the feedstream comprised both ethanol and water. The catalysts shown below in Table 7 were tested with both a pure anhydrous ethanol feedstream, and a feedstream comprising 85% ethanol and 15% water.

TABLE-US-00019 TABLE 7 Catalyst Mass of catalyst (mg) Mass of SiC (mg) P1/ZSM5-30 150 50 P3/ZSM5-30 150 150 P1/ZSM5-80 150 150 B1/ZSM5-30 150 150 B1/ZSM5-80 150 150 B3/ZSM5-80 150 150

Reaction Conditions

[0199] Each catalyst was placed in a separate reaction vessel tube. After loading into the reaction vessel tubes, the tubes were heated under air flow to 475 C., and held for 3 hours. The tubes were cooled to 400 C. whilst purging with Argon and the reaction pressure set at 5 bar. Ethanol (or the ethanol/water mixture) was then introduced to each reaction vessel at a rate of 2.0 L/min at a temperature of 400 C. Argon was introduced at a rate of 1 ml/min per reaction vessel tube as the internal standard and nitrogen was introduced to each catalyst bed in each reaction vessel tube at a rate of 37.5 ml/min as a diluent gas. The purpose of the nitrogen diluent gas is simply to increase the space velocity for subsequent gas chromatography analysis. These reaction conditions were maintained for the duration of the experiment.

[0200] The results of the experiments are shown in FIGS. 38 to 41. The figures show the C3/C4 selectivities and the C3 selectivities of each of the different catalysts tested when an anhydrous ethanol feedstream is used, and when a 85:15 mixture of ethanol and water is used.

[0201] In the pure anhydrous ethanol experiments, all promoted catalysts showed improved catalyst lifetime over the baseline unpromoted ZSM5-30 catalyst with the exception of B1/ZSM5-30 and P1/ZSM5-30. However, these catalysts showed improved initial selectivity when compared to the baseline unpromoted ZSM5-30 catalysts. P1ZSM5-80 afforded very good catalyst stability with deactivation onset only after 16 days. B1ZSM5-80, B3ZSM5-80 and P3-ZSM5-30 also all afforded considerably better lifetime than the baseline zeolite.

[0202] For the aqueous ethanol experiments, all promoted catalysts showed improved catalyst lifetime in comparison to the unpromoted baseline ZSM5-30 catalyst, with the exception of P1-ZSM5-30. However, this catalyst showed improved initial selectivity than the unpromoted baseline ZSM5-30 catalyst. All of the zeolite catalysts showed improved catalyst lifetime when using aqueous ethanol instead of pure anhydrous ethanol. The two outstanding zeolite catalysts were P1ZSM5-80 which showed remarkable catalyst stability and lifetime, and P1ZSM5-30 which showed excellent C3 selectivity.

Example 7

[0203] It was decided to investigate the catalytic activity of the catalyst using a different alcohol in the feedstream. Tests were undertaken on a pure iso-propanol (IPA) feedstream and a mixture of ethanol and iso-propanol. The same catalysts as listed above in Table 7 were tested under the same reaction conditions as specified in Example 6.

Results for a 1:1 Mixture of IPA and Ethanol

[0204] The results for P3ZSM5-30 and B1ZSM5-30 are shown in FIGS. 42 and 43 respectively. The results for the other zeolites (not shown) were broadly the same. It can be seen that both zeolites showed C3 and C4 hydrocarbon selectivity. The phosphorus promoted catalyst did not deactivate during the test period, whereas the boron promoted catalyst started to deactivate after around 10 days. Overall the use of ethanol/IPA for LPG formation showed results at least on par with when pure ethanol was used and therefore show that an IPA/ethanol mixture be a viable alternative bio-feedstock.

Results for Pure IPA

[0205] The results for P1ZSM5-30 and P1ZSM5-80 are shown in FIGS. 44 and 45 respectively. The results for the other zeolites (not shown) were broadly the same. The overall C3C4 selectivities (50-57%) when using IPA was higher than the corresponding ethanol/IPA (35-43%) and pure ethanol (35-43%) reactions. It is postulated that this may be due to the C3 feed being less likely to convert to heavier hydrocarbons and aromatics and hence a larger proportion of feed is converted to propane and iso-butane. None of the catalyst showed any signs of deactivation whatsoever over the twelve day testing period. The P1ZSM5-80 catalyst provided the best propane selectivity over the time online. In conclusion, the experiments have shown that pure IPA can be used as a conversion feedstock for LPG formation.

Example 8

[0206] Characterisation of various promoted zeolite catalyst materials was carried out using ammonia temperature programmed desorption (NH3-TPD), using the following experimental protocol.

Experimental Protocol

[0207] Ammonia temperature programmed desorption (NH3-TPD) experiments were carried out in a Micromeritics 2920, which is equipped with a TCD detector and coupled to a Balzers Thermostar quadrupole mass spectrometer which allows the analysis and monitoring of gaseous products as a function of time or sample temperature. Around 80 mg of sample were loaded in the U-shaped tube and attached to the instrument. The sample was then dried under a flow of argon in a two steps process, at 120 C. for 30 min and 500 C. for 20 min. Then, the sample is cooled down to 100 C. and saturated with NH3 by flowing 5% NH3/He for 1 hour at this temperature, followed by an evacuation step of 1 hour. Then, the sample is heated up to 500 C. to desorb NH3, with both TCD and MS monitoring the effluent gas during the desorption step. The cation m/z 17 was detected to monitor NH.sub.3.sup.+ ions profiles.

Results

[0208] FIG. 46 shows the NH3-TPD profile of unpromoted zeolite H-ZSM5-30 contrasted with those of various promoted H-ZSM5-30 materials that were synthesised. FIG. 47 shows the NH3-TPD profile of unpromoted zeolite H-ZSM5-80 contrasted with those of various promoted H-ZSM5-80 materials that were synthesised.

[0209] It can be seen that the addition of promoter elements affects the TPD spectra of the zeolites. For the phosphorus and boron promoted zeolites, it can be seen that the lower temperature peak increases and the higher temperature peak decreases relative to the corresponding unpromoted zeolite material. This is indicative of a change in the acid site distribution of the catalyst. Specifically, this is indicative of an increase in the number of weak acid sites and a decrease in the number of strong acid sites, relative to the corresponding unpromoted zeolite material.

[0210] The data in table 8 below shows the total desorption for various promoted zeolites.

TABLE-US-00020 TABLE 8 Total Desorption Total Desorption H-ZSM5 m/z 17 Norm. Area H-ZSM5 m/z 17 Norm. Area (30) series (1010) (80) series (1010) H-ZSM5-30 2.49 H-ZSM5-80 1.39 B1/ZSM5-30 2.74 B1/ZSM5-80 1.32 B3/ZSM5-30 2.32 B3/ZSM5-80 1.70 P1/ZSM5-30 1.93 P1/ZSM5-80 1.24 P2/ZSM5-30 0.96 P2/ZSM5-80 0.99 P3/ZSM5-30 1.25 P3/ZSM5-80 1.16

[0211] The data in Table 8 shows that all boron and phosphorus promoted zeolites with the exception of B1/ZSM5-30 and B3ZSM5-80 had a lower acid site density than the corresponding baseline unpromoted zeolite material. This, combined with the altered acid site distribution discussed above, means that these promoted zeolites all had reduced total acidity compared to the corresponding unpromoted baseline zeolite material. The promoted zeolites B1/ZSM5-30 and B3ZSM5-80 had increased acid site density compared to the baseline unpromoted zeolite material. However, these zeolites still had a lower overall total acidity compared to the corresponding unpromoted baseline zeolite material due to the shifted acid site distribution discussed above where the promoted zeolites have more weak acid sites and less strong acid sites than the corresponding baseline unpromoted zeolite materials.

[0212] FIG. 48 shows the TPD spectrum for various promoted MCM22 zeolites compared to the baseline unpromoted MCM22 zeolite. It can be seen that all promoted zeolites had a shifted acid site distribution such that there more weak acid sites and less strong acid sites compared to the corresponding unpromoted baseline zeolite material. The total desorption (m/z 17 Norm. Area (10-10)) for unpromoted MCM22 was 2.15, whereas for the B1 and B3 promoted materials it was 2.20 and 2.17 respectively. This is a incremental increase in the total number of acid sites. However, the significantly shifted acid site distribution in favour of weak acid sites means that the overall acidity of the boron promoted zeolites will be lower.

Example 9

[0213] The porosity of a variety of unpromoted and promoted zeolite catalysts was investigated. All samples were measured with a Micromeritics Gemini VI instrument. The surface area was calculated using the Brunauer, Emmett and Teller (BET) transformation. The pore volume and area distribution were calculated using the Barret, Joyner and Helnda (BJH) method. The measurements are shown in the tables provided in FIGS. 49 and 50. All samples show a very similar isotherm typical of ZSM5 zeolites with a hysteresis loop confirming type-IV behaviour. FIGS. 51 to 56 show the linear isotherms of the zeolite materials.

Example 10

[0214] Further experiments were carried out to determine the performance of zeolite catalysts under different reaction conditions. The catalysts tested were ZSM5-80, P1ZSM5-30 and P1ZSM5-80.

[0215] The results of these experiments are shown in FIGS. 55 to 62.

[0216] FIGS. 55 and 56 show the effect of different temperatures on the yield of C3 hydrocarbons and the sum of C3 and C4 hydrocarbons. Temperatures of 375 C., 400 C. and 425 C. are tested.

[0217] FIGS. 57 and 58 show the effect of different inert gas (argon) flow rates on the yield of C3 hydrocarbons and the sum of C3 and C4 hydrocarbons. Flow rates of 7 ml/minute/gram of catalyst, 15 ml/minute per gram of catalyst and 30 ml/minute per gram of catalyst were tested. This corresponds to 1.05 ml/minute/150 mg of catalyst, 2.25 ml/minute/150 mg of catalyst and 4.5 ml/minute/150 mg of catalyst respectively.

[0218] FIGS. 59 and 60 show the effect of different alcohol flow rates on the yield of C3 hydrocarbons and the sum of C3 and C4 hydrocarbons. Flow rates of 10 l/minute per gram of catalyst, 20 l/minute per gram of catalyst, 40 l/minute per gram of catalyst and 60 l/minute per gram of catalyst were tested. This corresponds to 1.5 l/min per 150 mg of catalyst, 3 l/min per 150 mg of catalyst, 6 l/min per 150 mg of catalyst and 9 l/min per 150 mg of catalyst respectively.

[0219] FIGS. 61 and 62 show the effect of different pressures on the yield of C3 hydrocarbons and the sum of C3 and C4 hydrocarbons. Pressures of 1 bar, 5 bar and 10 bar were tested.

[0220] The results of the experiments shown in FIGS. 55 to 62 demonstrate that the general trends in selectivities of the three tested catalysts at different operating conditions were similar. The following observations can be made: [0221] Increased temperature produced higher overall yields for the sum of C3 and C4 hydrocarbons. [0222] Higher inert gas flow rates over the catalyst bed also increased the yield of the sum of C3 and C4 hydrocarbons. The higher inert gas flow rates also caused lower amounts of aromatics to be produced as a by-product. [0223] A lower ethanol flow rate increased the yield of both C3 hydrocarbons, and the sum of C3 and C4 hydrocarbons. [0224] A higher reaction pressure desirably increased the amount of propane in the product stream. However, higher pressure also caused increased aromatics formation. As a result, the yield for the sum of C3 and C4 hydrocarbons was still highest at lower pressures.