Methods and systems for acoustically-assisted hydroprocessing at low pressure

Abstract

Hydroprocessing can be performed at low pressure using acoustic energy. For example, hydroprocessing a feedstock having one or more hydrocarbon compounds carried in, or mixed with, a transport gas involves flowing the feedstock through a reaction zone in a reactor that has a bulk pressure less than 68 atm and applying acoustic energy through the reaction zone. The hydrocarbon compounds are chemically reacted with a hydrogen source in the presence of a catalyst, wherein the reacting occurs in the reaction zone.

Claims

1. A method of hydroprocessing a feedstock, the method comprising: flowing the feedstock through a reaction zone in a reactor, the reaction zone having a bulk pressure less than 3 atm, wherein the feedstock comprises one or more hydrocarbon compounds and a transport gas; inducing acoustic streaming in the reaction zone by applying acoustic energy through the reaction zone; and chemically reacting the hydrocarbon compounds with a hydrogen source in the presence of a catalyst in the reaction zone, in the presence of the induced acoustic streaming.

2. The method of claim 1 wherein the hydrocarbon compounds comprise solid particulates.

3. The method of claim 1 wherein the hydrocarbon compounds comprise liquid fluid.

4. The method of claim 1 wherein the hydrocarbon compounds comprise vapor.

5. The method of claim 1 wherein the reaction zone has a bulk pressure approximately equivalent to atmospheric pressure.

6. The method of claim 1 wherein the hydrocarbon compounds comprise derivatives or distillate cuts of oils, tars, or asphaltenes.

7. The method of claim 6 wherein the oil, tars, or asphaltenes comprise petroleum, coal-derived oils, biomass-derived oils, oil sands, and/or oils shale.

8. The method of claim 1 wherein the hydrogen source comprises one or more of the following: hydrogen, methane, natural gas, or light hydrocarbons (C4).

9. The method of claim 1 having a liquid hourly space velocity (LHSV) greater than 0.1 hr.sup.1.

10. The method of claim 1 wherein the reaction zone has a bulk temperature from 120 C. to 450 C.

11. The method of claim 1 wherein said reacting comprises a reaction selected from the group consisting of hydrogenation, hydrocracking, hydrodesulfurization, hydrodenitrogenation, hydrodeoxygenation, hydrodemetalization, and combinations thereof.

12. A method of hydroprocessing a feedstock, the method comprising: flowing the feedstock through a reaction zone in a reactor, the reaction zone having a bulk pressure less than 68 atm, wherein the feedstock comprises one or more hydrocarbon compounds and a transport gas; inducing acoustic streaming in the reaction zone by applying acoustic energy through the reaction zone; and chemically reacting the hydrocarbon compounds with a hydrogen source in the presence of a catalyst in the reaction zone, in the presence of the induced acoustic streaming, wherein the acoustic streaming is characterized by a Reynolds number between about 1 to about 200.

Description

DESCRIPTION OF DRAWINGS

(1) Embodiments of the invention are described below with reference to the following accompanying drawings.

(2) FIG. 1 is a schematic depicting a tubular system for hydroprocessing a feedstock using acoustic energy according to embodiments of the present invention.

(3) FIG. 2 is a schematic depicting a system for hydroprocessing a feedstock using acoustic energy according to embodiments of the present invention.

(4) FIG. 3 is a graph depicting equilibrium amounts of various compounds as a function of temperature corresponding to operating conditions of Example 1

(5) FIG. 4 is a gas chromatogram of a product sample obtained from a feed comprising aromatics after processing according to embodiments of the present invention.

(6) FIG. 5 is a plot of the catalytic bed temperature (center of catalytic bed) as a function of time on stream corresponding to example 1

(7) FIG. 6 is a plot of the catalyst bed temperature as a function of time on stream corresponding to example 2 where not acoustic energy was applied for the first 30 minutes on steam or after 135 minutes on stream

(8) FIG. 7 is a plot of the catalyst bed temperature as a function of time on stream for example 3, where acoustic energy was applied throughout the entire duration of testing.

(9) FIG. 8 is a plot of the catalyst bed temperature as a function of time on stream for example 4, where the conditions are the same as example 3 but not acoustic energy was applied throughout the duration of the experiment.

DETAILED DESCRIPTION

(10) The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore the present description should be seen as illustrative and not limiting. While the invention is susceptible of various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.

(11) FIGS. 1-4 show a variety of aspects and embodiments of the present invention. Referring first to FIG. 1, the diagram depicts one embodiment of a system 100 for hydroprocessing a feedstock. Acoustic energy is directed from a transducer 102 to a reaction zone 106 via a waveguide 103. The transducer and waveguide can be coupled to a reactor 101 at the reaction zone by a coupling device 104. One example includes, but is not limited to, a clamp. The reactor in this embodiment is tubular and the reaction zone comprises a volume containing a catalyst 105.

(12) The reactor is configured for vapor phase or mixed vapor and liquid phase operation. In some embodiments, the reactants can comprise a minor fraction of solid particulates and/or liquid fluid carried in, or mixed with, a transport or reactive gas. The system is configured such that during operation, hydrocarbons and a hydrogen source enter the reactor tube and pass through the reaction zone, which has a bulk pressure less than 68 atm and into which acoustic energy is imparted. Product collection and/or analysis can occur down stream of the reaction zone. In some embodiments, the reactor can be configured as a fluidized catalytic bed reactor or a moving catalytic bed reactor. This is, at least in part, enabled by the lower pressure operation relative to traditional hydroprocessing systems.

(13) FIG. 2 contains a diagram depicting another embodiment of a system 200. Radiating plates 204 provide acoustic energy from a transducer 202 and through a waveguide 203 to the reaction zone 206 of a reactor vessel 201. The reaction zone comprises a catalyst load 205. The waveguides and/or radiating plates can be arranged in a variety of orientations relative to the reactor vessel and/or reaction zone. Depending on the type of reactor (i.e., moving bed, fixed, bed, fluidized bed, etc.), the reactants can enter and products can exit at various positions of the reactor vessel (e.g., top, bottom, side, etc.).

(14) Referring to FIG. 3, a plot summarizes equilibrium amounts of trans-decalin, cis-decalin, tetralin, and naphthalene as a function of temperature for a fixed pressure of 1 atm with an 86% H.sub.2 feed, which corresponds to the conditions used in Example 1 below. Formation of toluene and methyl cyclohexane were suppressed to calculate only equilibrium naphthalene hydrogenation products of cis-decalin, trans-decalin, and tetralin.

Example 1

(15) Referring to FIG. 4, a gas chromatogram identifies the primary components of a product stream after hydrogenation of a feed comprising aromatics that include toluene and napthalene in a 3:1 wt:wt ratio of toluene to naphthalene using acoustic energy according to embodiments of the present invention. The product stream includes unreacted feed (toluene and naphthalene), methylcyclohexane as well as tetralin and decalin (a mixture of both cis and trans isomers), both of which result from the presence of the acoustic energy and are not expected without the acoustic energy. While FIG. 3 indicates the possibility of the presence of decalin based on equilibrium conditions, in practice they are almost always absent because of mass transport and kinetic limitations. It is significant that the chromatogram is clean and does not indicate the presence of other reaction products, within the detection limits of the GC.

(16) TABLE-US-00001 TABLE 1 Summary of reaction conditions and compositions for a feed stream and four resulting samples Feed Sample 1 Sample 2 Sample 3 Conditions Temperature, C. 170-215 215-265 265-240 WHSV (hr.sup.1) 5.28 5.28 5.28 H.sub.2, mol % of feed 86 86 86 Acoustic Power, W 300 W 300 W 0 Sampling time, min 30 30 30 temperature rise during 45 50 25 sampling time, C. average Temperature, C. 198 232 242 Composition methyl-cyclohexane, wt % 0 39.5 9.2 n.d. Other alkyl naphthalene 0.13 .15 n.d. (C7), wt % Toluene, wt % 74.8 42.78 66.9 77.2 t-decalin, wt % 11.92 6.9 n.d. c-decalin, wt % 0 1.2 1.2 n.d. tetralin, wt % 0 1.93 7.5 7.6 naphthalene, wt % 25.2 2.97 4.3 9.01 TOTAL, wt % 100 100.43 96.26 93.82 Toluene conversion, % 43.1 7.0 7.5 naphthalene conversion, % 88.2 82.9 57 Equilibrium naphthalene 98.4 96.4 90.7 conversion, % Selectivity of toluene to 97.2 99 3 methylcyclohexane selectivity of naphthalene to 95.8 51 0 decalin (c + t) selectivity of naphthalene to 4.8 49 90 tetralin n.d.not detected/below detection limit

(17) Elaborating on the data shown in FIG. 4, acoustic energy was utilized according to embodiments of the present invention for the vapor phase, low pressure hydrogenation of aromatics to cyclic paraffins. A 3:1 mixture of toluene:naphthalene was co-fed with hydrogen into the acoustic reaction zone. Various trials were performed with and without acoustic energy at approximately atmospheric pressure. Table 1 provides a summary of the reaction conditions and compositions for the feed stream at three different time intervals (labeled as Sample 1-3) wherein the experiment conditions between samples 1 and 2 were identical, with the exception of the catalytic bed temperature increasing due to the exothermic nature of the hydrogenation reactions. For sample 3, acoustic energy was not applied. The temperature during each interval differed because the hydrogenation reaction is very exothermic, causing an increase in temperature as the reaction progressed. FIG. 5 shows the temperature profile of the catalytic bed as a function of the time on stream with corresponding notation indicating when samples 1-3 were collected and the time when acoustic energy was turned on and off.

(18) The equilibrium amounts of trans-decalin, cis-decalin, tetralin, toluene, methyl cyclohexane, and naphthalene at variable temperatures and a fixed pressure of 1 atm with an 86% H.sub.2 feed are provided. Without imparting acoustic energy into the reaction zone (see Sample 3), approximately 57% of the naphthalene was converted and only tetralin was formed. Effectively no toluene was converted and no methyl cyclohexane was formed. The 7% toluene conversion is believed to be due to the formation of toluene from naphthalene conversion. When acoustic energy was imparted and with temperatures between 170 C. and 215 C. (see Sample 1), approximately 88% of the naphthalene was converted and approximately 43% of the toluene was converted to methylcyclohexane. The converted naphthalene comprised 79% trans decalin, 8% cis decalin, and 13% tetralin. At temperatures between 215 C. and 265 C. with acoustic energy (see Sample 2), approximately 83% of the naphthalene was converted and approximately 8% of the toluene was converted to methylcyclohexane. The converted naphthalene comprises 44% trans decalin, 7% cis decalin, and 49% tetralin.

Examples 2

(19) In another example, the same reaction mixture comprising a 3:1 blend of toluene and naphthalene was co-fed into the acoustic reaction zone, which contained a commercially available hydrogenation catalyst. FIG. 6 shows the temperature profile of the catalyst bed throughout the course of experimentation. For the first 30 minutes on stream, no acoustic energy was applied and the temperature profile of the catalyst bed remains relatively constant at a temperature of 175 C. At a time on stream from 30 minutes through 130 minutes, acoustic energy was applied to the catalyst bed. Immediately upon turning on the acoustic energy, the bed temperature rapidly increased by 20 C. to a temperature of 195 C. Throughout the 100 minutes when acoustic energy is applied, the catalyst bed temperature steadily increased to a temperature of 252 C. Once the acoustic energy was turned off at a time on stream of 130 minutes the temperature of the catalyst bed steadily decreased. Based on the exothermic nature of the hydrogenation reactions occurring, the increasing temperature of the catalyst bed when acoustic energy is applied to the catalyst bed is a clear indication of hydrogenation activity at atmospheric pressure. Hydrogenation activity is believed to be absent when acoustic energy is not applied since the temperature of the catalyst bed remains constant or is reduced.

Examples 3

(20) A complex feed mixture can be fed through the system with a composition shown in Table 2. In the instant example, the experimental conditions were kept as constant as possible with the exception of the applied acoustic energy. No acoustic energy was applied and the results are representative of the degree of hydrogenation and desulfurization achievable under the such a system. FIG. 7 shows the temperature profile for as measured at the top and the bottom of the bed. When the feed is initially introduced, there is a slight increase in temperature by 3 C. at the top of the bed due to feed preheating at 300 C. However, the temperature at both the top and bottom of the bed remains relatively constant throughout the entire experiment. The lack of temperature rise indicates little to no hydrogenation or desulfurization of the feedstock, which is confirmed by product analysis shown in Table 3. Table 3 shows that the incoming feed and outcoming product without acoustic energy applied has the same (within error) sulfur concentration and H/C ratio of the oil.

Example 4

(21) Under similar conditions to Example 3, Example 4 applies acoustic energy to the catalytic bed. FIG. 8 shows the temperature rise of the top and bottom of the catalyst bed. When acoustic energy is applied, there is a rapid increase in the temperature as measured at the top and bottom of the bed, indicating significant hydrogenation activity. Hydrogenation activity for when acoustic energy is applied to the system is confirmed by both the increase in temperature (even when the heater power for the catalyst zone is turned off) and by product analysis shown in Table 3. Table 3 shows reduction in sulfur content of the product oil collected after 30 minutes and 76 minutes on stream by 100% and 96%, respectively, when acoustic energy is applied. Correspondingly the H/C ratio of the oil product is improved from 1.24 to 1.44 and 1.34 after 30 minutes and 76 minutes on stream.

(22) TABLE-US-00002 TABLE 2 Feed Mixture for Examples 3 and 4 Containing 275 ppm S Wt % in Compound feed Napthalene 7.12 Phenanthrene 1.57 Anthracene 0.95 Acenaphthalene 3.15 1-methyl naphthalene 23.65 toluene 30.68 Decane 22.35 Benzene 10.40 methylbenzothiophene 0.13

(23) TABLE-US-00003 TABLE 3 Summary of Examples 3 and 4 Example 3 Example 4 Example 4 (TOS 0 to (TOS 0 to (TOS 30 to FEED 72 mins) 30 mins) 76 mins) CONDITIONS WHSV, hr1 5.1 5.2 5.2 H2/oil (scf/bbl) 11230 11230 11230 Acoustic Power, W 0 650 650 Feed Preheat Temp, C. 300 300 300 Wall Temperature Set, 300 260 35 C. COMPOSITIONS H/C Ratio 1.24 1.25 1.44 1.34 Sulfur Conc., ppmw 275 273 BDL 12 mass balance 99.56 94.94 99.54 BDL = below detection limit

(24) While a number of embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims, therefore, are intended to cover all such changes and modifications as they fall within the true spirit and scope of the invention.