Method for preparing aromatic hydrocarbons

Abstract

Disclosed is a method for preparing aromatic hydrocarbons, particularly relates to the preparation of the aromatic hydrocarbons by passing methanol and carbon monoxide through a reactor loaded with an acidic ZSM-5 molecular sieve catalyst containing no metal additive under reaction conditions. Compared with the prior art, the method provided by the present invention can improve and stabilize the selectivity to aromatic hydrocarbons, particularly BTX, by adding carbon monoxide in methanol aromatization, and also prolongs the single-pass life of the catalyst. The performance of an inactivated catalyst is not significantly degraded after repeated regenerations. Furthermore, the catalyst preparation process omits the step of adding a metal additive, so that not only the process is simplified, but also costs are greatly reduced, and environmental protection is facilitated.

Claims

1. A method for preparing aromatic hydrocarbons, wherein the method comprises passing methanol and carbon monoxide through a reactor loaded with an acidic ZSM-5 molecular sieve catalyst containing no metal additive, to prepare the aromatic hydrocarbons under reaction conditions, wherein the acidic ZSM-5 molecular sieve has not been impregnated, ion exchanged, or physically mixed with a metal additive, wherein the acidic ZSM-5 molecular sieve is a hydrogen-type ZSM-5 molecular sieve, and wherein a molar ratio of the methanol to the carbon monoxide is less than or equal to 1:20, and greater than or equal to 1:100.

2. The method according to claim 1, wherein an atomic ratio of silicon to aluminum (Si/Al) in the acidic ZSM-5 molecular sieve is in a range of 3-200.

3. The method according to claim 2, wherein the atomic ratio of silicon to aluminum (Si/Al) in the acidic ZSM-5 molecular sieve is in a range of 10-40.

4. The method according to claim 1, wherein the reaction conditions include: a reaction temperature in a range from 350 C. to 550 C., a reaction pressure in a range from 0.5 MPa to 10.0 MPa, and a mass space velocity of methanol in a range from 0.01 h.sup.1 to 20 h.sup.1.

5. The method according to claim 4, wherein the reaction temperature is in a range from 390 C. to 480 C., the reaction pressure is in a range from 3 MPa to 7 MPa, and the mass space velocity of methanol is in a range from 0.3 h.sup.1 to 3.0 h.sup.1.

6. The method according to claim 1, wherein the reactor is a fixed bed reactor, a moving bed reactor or a fluidized bed reactor for conducting a continuous reaction.

7. The method according to claim 6, wherein the reactor is a fixed bed reactor.

Description

DETAILED DESCRIPTION OF THE EMBODIMENT

(1) The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(2) The raw materials in the examples of the present invention are all commercially purchased, unless otherwise stated.

(3) The analytical methods and the calculation methods for conversion rate and selectivity in the examples are as follows:

(4) Automated analysis is performed using an Agilent 7890 gas chromatograph equipped with a gas autosampler, a TCD detector connected to a TDX-1 packed column and a FID detector connected to a FFAP capillary column.

(5) In some examples of the present invention, both the conversion rate and the selectivity are calculated based on the mole number of carbon:

(6) The conversion rate of methanol=[(mole number of carbon in methanol in the feed)(mole number of carbon in methanol in the discharge)](mole number of carbon in methanol in the feed)100%

(7) The selectivity to liquid hydrocarbons (hydrocarbons containing 5 carbons or more)=(mole number of carbon in liquid hydrocarbons in the discharge)(mole number of carbon in all products in the discharge)100%

(8) The selectivity to aromatic hydrocarbons=(mole number of carbon in aromatic hydrocarbons in the discharge)(mole number of carbon in all products in the discharge)100%

(9) The selectivity to BTX=(mole number of carbon in BTX in the discharge)(mole number of carbon in all products in the discharge)100%

Example 1

(10) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=19 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (19), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=350, reaction pressure (P)=0.5 MPa, mass space velocity of methanol (WHSV)=0.01 h.sup.1, carbon monoxide:methanol (CO:MeOH)=1:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 2

(11) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=200 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (200), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=550, reaction pressure (P)=10 MPa, mass space velocity of methanol (WHSV)=20 h.sup.1, carbon monoxide:methanol (CO:MeOH)=100:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 3

(12) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=4 (atomic ratio) (purchased from Shanghai Zhuoyue company), abbreviated as HZSM-5 (4), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=450, reaction pressure (P)=5 MPa, mass space velocity of methanol (WHSV)=2 h.sup.1, carbon monoxide:methanol (CO:MeOH)=40:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 4

(13) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=70 (atomic ratio) (purchased from Shanghai Zhuoyue company), abbreviated as HZSM-5 (70), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, carbon monoxide:methanol (CO:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 5

(14) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=40 (atomic ratio) (purchased from Shanghai Zhuoyue company), abbreviated as HZSM-5 (40), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, carbon monoxide:methanol (CO:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 6

(15) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=25 (atomic ratio) (purchased from AOKE company), abbreviated as HZSM-5 (25), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, carbon monoxide:methanol (CO:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 7

(16) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=25 (atomic ratio) (purchased from AOKE company), abbreviated as HZSM-5 (25), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=390, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=0.3 h.sup.1, carbon monoxide:methanol (CO:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 8

(17) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=25 (atomic ratio) (purchased from AOKE company), abbreviated as HZSM-5 (25), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=480, reaction pressure (P)=7 MPa, mass space velocity of methanol (WHSV)=3 h.sup.1, carbon monoxide:methanol (CO:MeOH)=100:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Example 9

(18) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=30 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (30), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, carbon monoxide:methanol (CO:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Comparative Example 1

(19) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=30 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (30), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, nitrogen:methanol (N.sub.2:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Comparative Example 2

(20) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=30 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (30), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=0.1 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, nitrogen:methanol (N.sub.2:MeOH)=20:1. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

Comparative Example 3

(21) 10 g hydrogen-type ZSM-5 molecular sieve with Si/Al=30 (atomic ratio) (purchased from Catalyst Factory of Nankai University), abbreviated as HZSM-5 (30), is tableted and sieved to obtain particles of 20-40 mesh, which are then filled into a stainless steel reaction tube with an inner diameter of 16 mm, and activated at 550 for 4 hours with nitrogen of 100 ml/min. The reaction is carried out under the following conditions: reaction temperature (T)=400, reaction pressure (P)=3 MPa, mass space velocity of methanol (WHSV)=1 h.sup.1, and no other carrier gas is present. After the reaction is stabilized, the product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

(22) TABLE-US-00001 TABLE 1 Catalytic reaction results in Examples 1-7 and Comparative examples 1-3 Conversion Selectivity to Selectivity to Example/ Reaction rate of liquid aromatic Selectivity Comparative time methanol hydrocarbons hydrocarbons to BTX example Catalyst Reaction condition (h) (%) (%) (%) (%) Example 1 HZSM-5 (19) T = 350 ; 5 100 74.3 68.9 63.4 P = 0.5 MPa; WHSV = 0.01 h.sup.1; CO:MeOH = 1:1 Example 2 HZSM-5 (200) T = 550 ; 5 100 76.8 70.6 65.8 P = 10 MPa; WHSV = 20 h.sup.1; CO:MeOH = 100:1 Example 3 HZSM-5 (4) T = 450 ; 5 100 80.0 72.3 66.6 P = 5 MPa; WHSV = 2 h.sup.1; CO:MeOH = 40:1 Example 4 HZSM-5 (70) T = 400 ; 5 100 82.9 74.8 70.8 P = 3 MPa; WHSV = 1 h.sup.1; CO:MeOH = 20:1 Example 5 HZSM-5 (40) T = 400 ; 5 100 80.3 71.7 68.2 P = 3 MPa; WHSV = 1 h.sup.1; CO:MeOH = 20:1 Example 6 HZSM-5 (25) T = 400 ; 5 100 82.4 73.4 69.9 P = 3 MPa; WHSV = 1 h.sup.1; CO:MeOH = 20:1 Example 7 HZSM-5 (25) T = 390 ; 5 100 79.8 71.8 70.0 P = 3 MPa; WHSV = 0.3 h.sup.1; CO:MeOH = 20:1 Example 8 HZSM-5 (25) T = 480 ; 5 100 78.5 72.2 71.6 P = 7 MPa; WHSV = 3.0 h.sup.1; CO:MeOH = 100:1 Example 9 HZSM-5 (30) T = 400 ; 5 100 82.5 76.6 71.9 P = 3 MPa; 20 100 82.4 76.6 71.8 WHSV = 1 h.sup.1; 300 100 77.3 73.2 66.4 CO:MeOH = 20:1 Comparative HZSM-5 (30) T = 400 ; 5 100 57.3 30.5 24.4 example 1 P = 3 MPa; 20 100 48.6 25.4 20.0 WHSV = 1 h.sup.1; 100 50.8 15.4 3.1 1.5 N.sub.2:MeOH = 20:1 Comparative HZSM-5 (30) T = 400 ; 5 100 60.7 36.7 30.9 example 2 P = 0.1 MPa; 20 100 41.0 28.9 22.2 WHSV = 1 h.sup.1; 100 37.8 10.9 2.5 1.1 N.sub.2:MeOH = 20:1 Comparative HZSM-5 (30) T = 400 ; 5 100 56.7 35.5 31.7 example 3 P = 3 MPa; 20 100 44.3 27.9 21.2 WHSV = 1 h.sup.1; 100 45.1 14.8 3.7 2.1

Regeneration Performance Test of Catalyst

Example 10

(23) The deactivated catalyst in Example 9 is treated at 550 for 10 hours with a gas mixture comprising 2% oxygen and 98% nitrogen by volume fraction, so that the catalyst is regenerated for one cycle and used in the reaction carried out under the conditions of Example 9. Five cycles of regeneration are conducted in the same manner, and the catalytic activity data after 20 hours of reaction for each cycle is selected for comparison. The results are shown in Table 2.

Comparative Example 4

(24) The HZSM-5 (30) in Example 9 is impregnated with a zinc nitrate solution by an equal-volume method, dried and calcined at 550 to obtain an acidic ZSM-5 molecular sieve with a zinc content of 2%, abbreviated as Zn/HZSM-5 (30). The catalyst is used in the reaction carried out under the conditions of Example 9, and is regenerated under the conditions of Example 10, so that the catalyst is regenerated for one cycle and used in the reaction carried out under the conditions of Example 9. Five cycles of regeneration are conducted in the same manner, and the catalytic activity data after 20 hours of reaction for each cycle is selected for comparison. The results are shown in Table 2.

(25) TABLE-US-00002 TABLE 2 Catalytic reaction results in Example 10 and Comparative example 4 Conversion Selectivity to Selectivity to Example/ Fresh/Cycle rate of liquid aromatic Selectivity Comparative times of methanol hydrocarbons hydrocarbons to BTX Life example Catalyst regeneration (%) (%) (%) (%) (h) Example 10 HZSM-5 (30) Fresh 100 82.4 76.6 71.8 1200 Regeneration 100 83.3 75.8 72.0 1300 First cycle Regeneration 100 82.9 76.1 71.9 1150 Second cycle Regeneration 100 83.0 75.9 71.8 1250 Third cycle Regeneration 100 82.8 75.6 71.3 1200 Fourth cycle Regeneration 100 83.2 76.0 72.1 1180 Fifth cycle Comparative Zn/HZSM-5 (30) Fresh 100 80.0 75.8 68.9 500 example 4 Regeneration 100 75.6 70.2 60.6 350 First cycle Regeneration 100 70.5 62.9 54.7 280 Second cycle Regeneration 100 60.2 50.3 41.9 190 Third cycle Regeneration 100 58.8 48.7 37.9 150 Fourth cycle Regeneration 100 53.9 44.6 32.1 120 Fifth cycle

(26) It can be seen from Table 2 that the acidic ZSM-5 molecular sieve containing no metal additive after regeneration has a significant improvement in the selectivity to aromatic hydrocarbons and BTX and the catalyst life.

(27) The above are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application is disclosed by the preferred embodiments as above, they are however not used to limit the present application. A slight change or modification utilizing the technical content disclosed above made by the person skilled in art, without departing from the technical solution of the present application, is equivalent to the equivalent embodiment, and falls within the scope of the technical solution.