Process for converting paraffin to olefin and catalyst for use therein

Abstract

The invention relates to a process for converting paraffin to olefin comprising the following steps: (a) providing a hydrocarbon feedstock containing at least one paraffin having 1 to 12 carbon atoms and at least one olefin having 2 to 12 carbon atoms; (b) providing a catalyst containing at least one Group VIA and/or Group VIIA transition metal on a solid support; (c) pretreating the catalyst by contacting the catalyst with at least one reducing gas and at least one oxidizing gas; and (d) contacting the by hydrocarbon feedstock and the pretreated catalyst at a temperature in the range of 200 C. to 600 C., preferably 320 C. to 450 C. and to a catalyst for use therein.

Claims

1. A process for converting paraffin to olefin comprising the following steps: (a) providing a hydrocarbon feedstock containing at least one paraffin having 1 to 12 carbon atoms and at least one olefin having 2 to 12 carbon atoms; (b) providing a catalyst containing a single metal on a solid support, wherein the single metal is a Group VIA transition metal; (c) pretreating the catalyst by contacting the catalyst with at least one reducing gas and at least one oxidizing gas; and (d) contacting the hydrocarbon feedstock with the pretreated catalyst at a temperature in the range of 200 C. to 600 C. to thereby form ethylene and propylene with a selectivity for ethylene and propylene of at least 88 wt %.

2. The process according to claim 1, wherein the at least one paraffin is methane, ethane, propane, n-butane, i-butane, n-pentane, i-pentane or mixtures thereof.

3. The process according to claim 1, wherein the at least one olefin is ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, n-pentene or mixtures thereof.

4. The process according to claim 1, wherein the weight ratio of paraffins to olefins in the hydrocarbon feedstock is in the range of 0.1:1 to 100:1.

5. The process according to claim 1, wherein the Group VIA transition metal is molybdenum or tungsten.

6. The process according to claim 1, wherein the catalyst comprises 1 to 15 percent by weight of the Group VIA transition metal based on total weight of the catalyst.

7. The process according to claim 1, wherein the solid support is silicon dioxide, aluminum oxide, activated carbon, magnesium oxide, titanium dioxide, lanthanum oxide, zirconium dioxide, zeolite, layered double hydroxides or any combination thereof.

8. The process according to claim 1, wherein pretreating the catalyst comprises contacting the catalyst with the at least one reducing gas at a temperature in the range of 200 C. to 700 C.

9. The process according to claim 8, wherein the reducing gas is hydrogen.

10. The process according to claim 8, wherein the contacting the catalyst with the at least one reducing gas is done with a WHSV in the range of 0.0001 hr.sup.1 to 100 hr.sup.1 for a period of 5 minutes to 30 hours.

11. The process according to claim 1, wherein pretreating the catalyst comprises contacting the catalyst with the at least one oxidizing gas at a temperature in the range of 200 C. to 700 C.

12. The process according to claim 11, wherein the oxidizing gas is air.

13. The process according to claim 11, wherein the contacting the catalyst with the at least one oxidizing gas is done with a WHSV in the range of 0.0001 hr.sup.1to 100 hr.sup.1 for a period of 5 minutes to 30 hours.

14. The process according to claim 1, wherein the pretreated catalyst comprises a mixture of at least one transition metal hydride and at least one transition metal oxide.

15. The process according to claim 1, wherein contacting the hydrocarbon feedstock with the pretreated catalyst in step (d) is carried out at a pressure in the range of 1 bar to 60 bar.

16. The process according to claim 1, wherein contacting the hydrocarbon feedstock and the pretreated catalyst in step (d) is carried out at a WHSV in the range of 0.01 hr.sup.1 to 200 hr.sup.1 .

17. The process according to claim 1, wherein the process further comprises a regeneration step (e).

18. The process according to claim 17, wherein the regeneration step (e) comprises contacting the catalyst with at least one oxidizing gas at a temperature in the range of 200 C. to 700 C.

19. The process according to claim 1, wherein the selectivity for ethylene and propylene ranges from 88 wt % to 97 wt %.

Description

EXAMPLES

(1) Examples 1 to 6 are illustrative of the process for converting paraffin to olefin according to this invention.

Example 1

(2) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(3) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(4) When bed temperature reached 350 C., feedstock containing 10 percent by weight of n-butane and 20 percent by weight of ethylene balancing with nitrogen was fed through the catalyst bed at flow rate 10-20 cc/min and pressure 20 barg.

(5) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffin conversions and olefin yields. The result of this experiment is shown in Table 1.

Example 2

(6) An experiment the same as in Example 1 was performed with a feedstock containing 10 percent by weight of i-butane and 20 percent by weight of ethylene balancing with nitrogen. The result of this experiment is shown in Table 1.

Example 3

(7) An experiment the same as in Example 1 was performed with a feedstock containing 10 percent by weight of propane and 20 percent by weight of ethylene balancing with nitrogen. The result of this experiment is shown in Table 1.

Example 4

(8) An experiment the same as in Example 1 was performed with a feedstock containing 10 percent by weight of LPG (containing 25 wt % propane, 25 wt % i-butane and 50 wt % n-butane) and 20 percent by weight of ethylene balancing with nitrogen. The result of this experiment is shown in Table 1.

Example 5

(9) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(10) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(11) When bed temperature reached 350 C., feedstock containing 4 percent by weight of n-butene and 6 percent by weight of n-butane and 20 percent by weight of ethylene balancing with nitrogen was fed through the catalyst bed at flow rate 5-20 cc/min and pressure 20 barg.

(12) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

Example 6

(13) This example is illustrative of the process for converting paraffin to olefin according to this invention.

(14) An experiment the same as in Example 1 was performed without magnesium oxide. The result of this experiment is shown in Table 1.

(15) Comparative examples A and B illustrate the effect of catalyst pretreatment conditions on the inventive process.

Comparative Example A

(16) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(17) After that the catalyst was pretreated by flowing 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour, and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(18) When bed temperature reached 350 C., feedstock containing 10 percent by weight of n-butane and 20 percent by weight of ethylene balancing with nitrogen was fed through the catalyst bed at flow rate 10-20 cc/min and pressure 20 barg.

(19) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

Comparative Example B

(20) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(21) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4, and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C. When bed temperature reached 350 C., feedstock containing 10 percent by weight of n-butane and 20 percent by weight of ethylene balancing with nitrogen was fed through the catalyst bed at flow rate 10-20 cc/min and pressure 20 barg.

(22) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

(23) Comparative examples C, D, E and F illustrate the effect of olefin co-feeding on the inventive process.

Comparative Example C

(24) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(25) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(26) When bed temperature reached 350 C., feedstock containing 10-20 percent by weight of n-butane balancing with nitrogen was fed through the catalyst bed at flow rate 5-20 cc/min and pressure 20 barg.

(27) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

Comparative Example D

(28) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(29) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 290 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(30) When bed temperature reached 350 C., feedstock containing 10-20 percent by weight of ethylene balancing with nitrogen was fed through the catalyst bed at flow rate 5-20 cc/min and pressure 20 barg.

(31) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

Comparative Example E

(32) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(33) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(34) When bed temperature reached 350 C., feedstock containing 10-20 percent by weight of i-Butane balancing with nitrogen was fed through the catalyst bed at flow rate 5-20 cc/min and pressure 20 barg.

(35) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

Comparative Example F

(36) 3 grams of catalyst comprising 8 percent by weight of tungsten on a solid support comprising 5 percent by weight of HY-zeolite and 95 percent by weight of silicon dioxide was mixed with 3 grams of magnesium oxide and then packed in a tubular reactor.

(37) After that the catalyst was pretreated by flowing air through the catalyst bed at a temperature of 500 C. and WHSV 0.30 hr.sup.1 for 4 hours, then subsequently flow 10 percent by volume of hydrogen gas balancing with nitrogen through the catalyst bed at a temperature of 400 C. and WHSV 0.002 hr.sup.1 for 1 hour and then raised temperature to 550 C. and hold for 2 hours before cooling down to reaction temperature at 350 C.

(38) When bed temperature reached 350 C., feedstock containing 10-20 percent by weight of propane balancing with nitrogen was fed through the catalyst bed at flow rate 5-20 cc/min and pressure 20 barg.

(39) Effluents from the reaction were directed to GC-FID (Agilent) to measure their chemical compositions. The measured compositions of effluents were used to calculate paraffins conversion and olefins yield. The result of this experiment is shown in Table 1.

(40) TABLE-US-00001 TABLE 1 Paraffin(s) Ethylene Propylene Conversion Selectivity Selectivity Example Feed Co-catalyst Pretreatment (wt %) (wt %) (wt %) Example 1 n-Butane MgO Air, H2 60 70 25 Ethylene Example 2 i-Butane MgO Air, H2 57 82 10 Ethylene Example 3 Propane MgO Air, H2 40 8 80 Ethylene Example 4 LPG MgO Air, H2 55 20 70 Ethylene Example 5 n-Butene MgO Air, H2 90 wt % of C4 hydrocarbon in feedstock n-Butane (n-Butene and n-Butane) was converted Ethylene to a product stream containing 64 wt % ethylene and 27 wt % propylene Example 6 n-Butane None Air, H2 66% 72% 25% Ethylene Comparative n-Butane MgO H2 No paraffin conversion. 40% of olefin Example A Ethylene was converted to 60 wt % propylene and 40 wt % n-butene Comparative n-Butane MgO Air No Reaction Example B Ethylene Comparative n-Butane MgO Air, H2 No Reaction Example C Comparative Ethylene MgO Air, H2 No Reaction Example D Comparative i-Butane MgO Air, H2 No Reaction Example E Comparative Propane MgO Air, H2 No Reaction Example F

(41) The paraffin conversions shown in Table 1 were calculated from weight of paraffin(s) converted during reaction divided by total weight of paraffin(s) in feedstock and then multiplies by one hundred. The ethylene and propylene selectivity shown in Table 1 were calculated from weight of ethylene or propylene produced from the reaction divided by weight of all products produced from the reaction and then multiplies by one hundred. The features disclosed in the foregoing description and in the claims may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.