CN110026232B - Method for preparing methyl mercaptan by extracting aluminum modified composite catalyst from phosphogypsum - Google Patents

Method for preparing methyl mercaptan by extracting aluminum modified composite catalyst from phosphogypsum Download PDF

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CN110026232B
CN110026232B CN201910331415.XA CN201910331415A CN110026232B CN 110026232 B CN110026232 B CN 110026232B CN 201910331415 A CN201910331415 A CN 201910331415A CN 110026232 B CN110026232 B CN 110026232B
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composite catalyst
methyl mercaptan
gamma
catalyst
zsm
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CN110026232A (en
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王乐
李小涛
林喜华
袁义进
赵士豪
路东义
何凯
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China West Construction Guizhou Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
    • C07C319/02—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of thiols
    • C07C319/08—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of thiols by replacement of hydroxy groups or etherified or esterified hydroxy groups

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Abstract

The invention discloses a method for preparing methyl mercaptan by extracting an aluminum modified composite catalyst from phosphogypsum, which comprises the following steps: the method comprises the following steps: acid leaching waste gypsum, separating and purifying aluminum to prepare gamma-Al2O3Using the prepared gamma-Al2O3ZSM-5 is modified by the sample to obtain the composite catalyst, and hydrogen sulfide gas and methanol gas are fully contacted and reacted with the catalyst to obtain a product methyl mercaptan. On one hand, the method removes part of impurities in the phosphogypsum, realizes the recycling of the phosphogypsum solid waste, and simultaneously utilizes the properties of the impurities to prepare the gamma-Al2O3The @ ZSM-5 composite catalyst has long service life, high selectivity of methyl mercaptan product and lowered reaction temperature.

Description

Method for preparing methyl mercaptan by extracting aluminum modified composite catalyst from phosphogypsum
Technical Field
The invention relates to a method for preparing methyl mercaptan by extracting an aluminum modified composite catalyst from phosphogypsum, belonging to the field of methyl mercaptan preparation.
Background
China CH3The conflict between supply and demand of SH market is very prominent, CH3The annual production of SH is less than 2 ten thousand tons, and the annual demand is as much as tens of thousands tons. Guizhou coal resources are rich, and how to solve coal-based CH in the process of vigorously developing coal chemical industry3OH supply greater than demand, and a large amount of H2The problem of resource utilization of S gas is very urgent. Therefore, according to the characteristics of mineral resources in Guizhou, the ratio of H to H is2S and CH3Catalytic synthesis of CH by taking OH as raw material3SH has stronger regional resource advantages. Not only has the advantages of sufficient raw materials, low cost and the like, but also can solve the problem of H2High-efficiency resource utilization of S gasWith a radical of formula (II) and (II)3The development of OH downstream products and other related problems can greatly relieve the environmental pollution problem possibly generated in the process of developing coal chemical industry, promote the maximization of resource utilization benefit, and H2S and CH3Catalytic synthesis of CH by taking OH as raw material3The chemical reaction equation for SH is as follows:
CH3OH+H2S→CH3SH+H2o (main reaction)
2CH3OH+H2S→(CH3)2S+H2O (side reaction)
2CH3SH→(CH3)2+H2S (side reaction).
The ZSM-5 catalyst has a larger pore structure and lower product selectivity in the field of preparing other chemical products by using methanol. ZSM-5 is modified by a method of preparing a hierarchical pore molecular sieve by modification, so that the pore channel becomes narrow, the shape selection function is enhanced, and the product selectivity is improved. In addition, in the reaction process of preparing other chemical products by using methanol, the temperature is mostly over 400 ℃, and the formation rate of carbon deposit and the reaction temperature are in exponential growth relationship, so that the service life of the catalyst is short. Therefore, the modified composite catalyst can reduce the reaction temperature of the system, effectively relieve the carbon deposition formation rate, prolong the service life of the catalyst and save the cost.
Phosphogypsum is the main solid waste in wet-process phosphoric acid industry, and is used for producing 1t wet-process phosphoric acid (P)2O5Calculated) will yield 4.5-5.0 t phosphogypsum. At present, the average utilization rate of the Chinese phosphogypsum is less than 10%, the rest phosphogypsum is still stacked in an open-air slag yard, and the random discharge of a large amount of phosphogypsum not only pollutes the environment, but also occupies a large amount of land and has potential environmental protection risks. In addition, a large amount of cost, money and labor are needed to be spent for treating the phosphogypsum stacking problem every year, and the fundamental problem cannot be solved. The phosphogypsum usually needs to be pretreated to remove impurities such as Al during solid waste treatment, and at present, the phosphogypsum is mainly treated by adopting a water washing mode, but the method mainly removes soluble P, and some valuable impurity ions also exist in the phosphogypsum.
Disclosure of Invention
Aiming at the problems, the invention aims to extract aluminum in the impurities of the phosphogypsum to obtain AlCl by an acid-base precipitation method according to the principle that the phosphogypsum contains the impurities of phosphoric acid, aluminum, silicon, iron and the like besides calcium sulfate as a main component3·6H2O, synthesis of gamma-Al with template agent2O3Is compounded with ZSM-5 catalyst to form gamma-Al2O3The @ ZSM-5 composite catalyst is used to solve the problems of low yield of target product, short catalyst reaction life and high reaction temperature in the process of synthesizing methyl mercaptan by hydrogen sulfide methanol method.
The purpose of the invention is realized by the following technical scheme:
a method for preparing methyl mercaptan by extracting aluminum modified composite catalyst from phosphogypsum comprises the following steps:
step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking supernate, adding sodium hydroxide solution, carrying out solid-liquid separation, taking supernate, adding dilute hydrochloric acid until white precipitates are completely dissolved, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O solution; the chemical reaction equation is as follows:
Al2O3+2NaOH＝2NaAlO2+H2O
white precipitate formed upon addition of dilute hydrochloric acid:
HCl+NaAlO2+H2O＝NaCl+Al(OH)3↓
with the addition of dilute hydrochloric acid, the hydrochloric acid was gradually in excess and the white precipitate dissolved:
Al(OH)3+3HCl＝AlCl3(aq)+3H2O
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Rate ofPump in 3 mol. L-1The precipitant is added until the pH value of the solution system is 8-9, the mixture is continuously stirred for 30min, aged in water bath at the temperature of 80 ℃ for 3h, cooled to room temperature, filtered, washed, dried at the temperature of 80 ℃ for 6 h-12 h to prepare a pseudoboehmite sample, and roasted at the temperature of 600 ℃ for 3h to prepare the gamma-Al2O3A sample;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst;
step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1Conveying the methanol solution into a fixed bed catalyst tube, converting the methanol solution into methanol gas at high temperature, and fully contacting and reacting the hydrogen sulfide gas and the methanol gas with the catalyst to obtain a product methyl mercaptan, wherein the molar ratio of the hydrogen sulfide to the methanol gas is H2S:CH3OH 2: 1. The first step of the reaction is that methanol is dissociated and adsorbed in an acid center to form a methoxy active state, methoxy can react with hydrogen sulfide molecules or dissociated sulfhydryl (SH-) thereof respectively to generate methyl mercaptan, the generation of the dissociated sulfhydryl in the reaction process is beneficial to improving the selectivity of the methyl mercaptan, and the ratio of the hydrogen sulfide to the methanol is improved to ensure that the excessive hydrogen sulfide is beneficial to the generation of the methyl mercaptan.
Further, the concentration of dilute hydrochloric acid in step 1.1 is 1 mol/L.
Further, gamma-Al in step 1.22O3The sample with 200 meshes is prepared by grinding and sieving.
Further, the precipitating agent in step 1.2 is NH3·H2O、Na2CO3Or NaHCO3One kind of (1).
Further, the modification treatment method in step 1.3 is as follows: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water under the condition of continuously stirringAdding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate to prepare a ZSM-5 precursor mixed solution, aging for 8-24h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1-3:1-3, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6 h-12 h, and roasting at 450-650 ℃ for 3h to obtain the gamma-Al after modification2O3@ ZSM-5 composite catalyst.
Further, in the modification treatment method of step 1.3, the aging time is 12 hours.
Further, in step 1.3 modification treatment method, γ -Al2O3The weight ratio of the active carbon to ZSM-5 is 1: 1.
Further, in the modification treatment method in the step 1.3, the roasting temperature is 500-600 ℃.
The principle of the invention is as follows:
prepared gamma-Al2O3The @ ZSM-5 composite catalyst is applied to the production process for preparing methyl mercaptan from methanol, and the B acid and the gamma-Al of the ZSM-5 composite catalyst of the modified composite catalyst2O3The L acid can form a B acid-L acid synergistic center and a B acid-L alkali center, so that the bottleneck problems of the adsorption dissociation degree of the methanol at a lower temperature and the rapid carbon deposition inactivation of the catalyst are solved; on the other hand, the micropores of ZSM-5 and gamma-Al2O3The mesopores can form a special hierarchical structure, so that the diffusion of molecules is weakened, the formation of carbon deposit of the ZSM-5 molecular sieve is relieved, and the service life of the catalyst is prolonged; meanwhile, the ZSM-5 special microporous structure is beneficial to strengthening the restriction effect of the composite catalyst, and further improves the selectivity of a target product. The invention prepares the gamma-Al2O3The @ ZSM-5 composite catalyst is applied to a chemical product process for preparing methyl mercaptan from methanol, has higher activity and higher product selectivity at lower temperature, and can greatly prolong the catalytic life of the ZSM-5 molecular sieve.
Compared with the prior art, the invention has obvious beneficial effects, and the technical scheme can show that: the invention provides gamma-Al2O3The @ ZSM-5 composite catalyst has long service life, high methyl mercaptan selectivity and low costThe temperature of the catalytic reaction.
The invention is further illustrated by the following specific examples.
Detailed Description
Comparative example 1:
the unmodified ZSM-5 catalyst is applied to the reaction of preparing methyl mercaptan from methanol.
Preparation of ZSM-5 catalyst: according to the mol ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water at normal temperature, continuously stirring, sequentially adding tetrapropylammonium hydroxide and ethyl orthosilicate to prepare a mixed solution, aging for 12 hours, carrying out microwave hydrothermal reaction at 180 ℃ for 2 hours, cooling, filtering, washing, drying at 105-110 ℃ for 6-12 hours, and roasting at 550 ℃ for 3 hours to obtain the ZSM-5 catalyst.
The ZSM-5 catalyst is applied to a process for preparing methyl mercaptan from methanol, and the reaction pressure is as follows: normal pressure, reaction temperature: 370 ℃, weight hourly space velocity: 1.5h-1The raw material feeding airspeed: 90 mL/min-1，H2S：CH3The OH molar ratio is 2:1, the selectivity of methyl mercaptan is 70.71 percent, and the service life is 6 h.
Comparative example 2:
the unmodified ZSM-5 catalyst is applied to the reaction of preparing methyl mercaptan from methanol.
Preparation of ZSM-5 catalyst: according to the mol ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water at normal temperature, continuously stirring, sequentially adding tetrapropylammonium hydroxide and ethyl orthosilicate to prepare a mixed solution, aging for 12 hours, carrying out microwave hydrothermal reaction at 180 ℃ for 2 hours, cooling, filtering, washing, drying at 105-110 ℃ for 6-12 hours, and roasting at 550 ℃ for 3 hours to obtain the ZSM-5 catalyst.
The ZSM-5 catalyst is applied to a process for preparing methyl mercaptan from methanol, and the reaction pressure is as follows: normal pressure, reaction temperature: 400 ℃, weight hourly space velocity: 1.5h-1The raw material feeding airspeed: 90 mL/min-1，H2S：CH3The OH molar ratio is 2:1, the selectivity of methyl mercaptan is 71.78 percent, and the service life is 7 h.
Example 1
Step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking the supernatant, adding a sodium hydroxide solution into the obtained supernatant, performing solid-liquid separation, taking the supernatant, adding dilute hydrochloric acid into the supernatant until all white precipitates are dissolved to generate an aluminum chloride solution, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O solution; wherein the concentration of the dilute hydrochloric acid is 1mol/L,
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1NH of (2)3·H2Adding O precipitant until the pH value of the solution system is 8-9, continuously stirring for 30min, aging in water bath at 80 ℃ for 3h, cooling to room temperature, filtering, washing, drying at 80 ℃ for 6-12 h to obtain pseudoboehmite sample, and roasting at 600 ℃ for 3h to obtain gamma-Al2O3Sample, gamma-Al2O3Grinding and sieving a sample to 200 meshes;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate while continuously stirring to prepare a ZSM-5 precursor mixed solution, aging for 12h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1:1, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6-12 h, and roasting at 450 ℃ for 3h to complete modification to obtain the gamma-Al2O3@ ZSM-5 composite catalyst.
Step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1And (2) conveying the methanol solution into a fixed bed catalyst tube, wherein the methanol solution is changed into methanol gas at high temperature, the hydrogen sulfide gas and the methanol gas are in full contact reaction with the catalyst to obtain a product methyl mercaptan, the selectivity of the methyl mercaptan is 80.2%, the service life of the composite catalyst is 8h, compared with the comparative example 1, the product selectivity is improved by 9.49%, and the service life of the composite catalyst is prolonged by 2h compared with that of an unmodified catalyst. Compared with comparative example 2, the product selectivity is improved by 8.42 percent, and the service life of the catalyst is prolonged by 1h compared with that of an unmodified catalyst.
Example 2
Step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking the supernatant, adding a sodium hydroxide solution into the obtained supernatant, performing solid-liquid separation, taking the supernatant, adding dilute hydrochloric acid into the supernatant until all white precipitates are dissolved to generate an aluminum chloride solution, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O solution; wherein the concentration of the dilute hydrochloric acid is 1mol/L,
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1NH of (2)3·H2Adding O precipitant until the pH value of the solution system is 8-9, continuously stirring for 30min, aging in water bath at 80 ℃ for 3h, cooling to room temperature, filtering, washing, drying at 80 ℃ for 6-12 h to obtain pseudoboehmite sample, and roasting at 600 ℃ for 3h to obtain gamma-Al2O3Sample, gamma-Al2O3Grinding and sieving a sample to 200 meshes;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate while continuously stirring to prepare a ZSM-5 precursor mixed solution, aging for 12h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1:1, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6-12 h, and roasting at 500 ℃ for 3h to complete modification to obtain the gamma-Al2O3@ ZSM-5 composite catalyst.
Step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1And (2) conveying the methanol solution into a fixed bed catalyst tube, wherein the methanol solution is changed into methanol gas at high temperature, the hydrogen sulfide gas and the methanol gas are in full contact reaction with the catalyst to obtain a product methyl mercaptan, the selectivity of the methyl mercaptan is 85.7%, the service life of the composite catalyst is 11.4h, compared with the comparative example 1, the product selectivity is improved by 14.99%, and the service life of the composite catalyst is prolonged by 5.4h compared with that of an unmodified catalyst. Compared with comparative example 2, the product selectivity is improved by 13.92%, and the service life of the catalyst is prolonged by 4.4h compared with that of an unmodified catalyst.
Example 3
Step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking the supernatant, adding a sodium hydroxide solution into the obtained supernatant, performing solid-liquid separation, taking the supernatant, adding dilute hydrochloric acid into the supernatant until all white precipitates are dissolved to generate an aluminum chloride solution, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O solution; wherein the dilute hydrochloric acid is concentratedThe degree of the reaction is 1mol/L,
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1NH of (2)3·H2Adding O precipitant until the pH value of the solution system is 8-9, continuously stirring for 30min, aging in water bath at 80 ℃ for 3h, cooling to room temperature, filtering, washing, drying at 80 ℃ for 6-12 h to obtain pseudoboehmite sample, and roasting at 600 ℃ for 3h to obtain gamma-Al2O3Sample, gamma-Al2O3Grinding and sieving a sample to 200 meshes;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate while continuously stirring to prepare a ZSM-5 precursor mixed solution, aging for 12h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1:1, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6 h-12 h, and roasting at 550 ℃ for 3h to complete modification to obtain the gamma-Al2O3@ ZSM-5 composite catalyst.
Step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1Conveying the methanol solution into a fixed bed catalyst tube, converting the methanol solution into methanol gas at high temperature, fully contacting and reacting the hydrogen sulfide gas and the methanol gas with the catalyst to obtain a product methyl mercaptan, wherein the selectivity of the methyl mercaptan is 89.46%, the service life of the composite catalyst is 18.5h, and the product is p-xyleneCompared with example 1, the product selectivity is improved by 18.75%, and the service life of the catalyst is prolonged by 12.5h compared with that of the unmodified catalyst. Compared with comparative example 2, the product selectivity is improved by 17.68%, and the service life of the catalyst is prolonged by 11.5h compared with that of an unmodified catalyst.
Example 4
Step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking the supernatant, adding a sodium hydroxide solution into the obtained supernatant, performing solid-liquid separation, taking the supernatant, adding dilute hydrochloric acid into the supernatant until all white precipitates are dissolved to generate an aluminum chloride solution, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O; wherein the concentration of the dilute hydrochloric acid is 1mol/L,
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1NH of (2)3·H2Adding O precipitant until the pH value of the solution system is 8-9, continuously stirring for 30min, aging in water bath at 80 ℃ for 3h, cooling to room temperature, filtering, washing, drying at 80 ℃ for 6-12 h to obtain pseudoboehmite sample, and roasting at 600 ℃ for 3h to obtain gamma-Al2O3Sample, gamma-Al2O3Grinding and sieving a sample to 200 meshes;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate while continuously stirring to prepare a ZSM-5 precursor mixed solution, aging for 12h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1:1, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing,drying at 105-110 ℃ for 6-12 h, and roasting at 600 ℃ for 3h to complete modification to obtain the gamma-Al2O3@ ZSM-5 composite catalyst.
Step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1And (2) conveying the methanol solution into a fixed bed catalyst tube, wherein the methanol solution is changed into methanol gas at high temperature, the hydrogen sulfide gas and the methanol gas are in full contact reaction with the catalyst to obtain a product methyl mercaptan, the selectivity of the methyl mercaptan is 82.2%, the service life of the composite catalyst is 10.1h, compared with the comparative example 1, the product selectivity is improved by 11.49%, and the service life of the composite catalyst is prolonged by 4.1h compared with that of an unmodified catalyst. Compared with the comparative example 2, the product selectivity is improved by 10.42 percent, and the service life of the catalyst is prolonged by 3.1 hours compared with that of an unmodified catalyst.
Example 5
Step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking the supernatant, adding a sodium hydroxide solution into the obtained supernatant, performing solid-liquid separation, taking the supernatant, adding dilute hydrochloric acid into the supernatant until all white precipitates are dissolved to generate an aluminum chloride solution, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O; wherein the concentration of the dilute hydrochloric acid is 1mol/L,
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1NH of (2)3·H2O precipitant until the pH value of the solution system is 8-9,continuously stirring for 30min, ageing in water bath at 80 ℃ for 3h, cooling to room temperature, filtering, washing, drying at 80 ℃ for 6-12 h to obtain pseudoboehmite sample, and roasting at 600 ℃ for 3h to obtain gamma-Al2O3Sample, gamma-Al2O3Grinding and sieving a sample to 200 meshes;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate while continuously stirring to prepare a ZSM-5 precursor mixed solution, aging for 12h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1:1, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6 h-12 h, and roasting at 650 ℃ for 3h to complete modification to obtain the gamma-Al2O3@ ZSM-5 composite catalyst.
Step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: under the action of carrier gas nitrogen, the prepared methanol solution is pumped by a peristaltic pump at an airspeed of 1.5h-1And (2) conveying the mixture into a fixed bed catalyst tube, changing methanol solution into methanol gas at high temperature, fully contacting and reacting hydrogen sulfide gas and the methanol gas with a catalyst to obtain a product methyl mercaptan, wherein the selectivity of the methyl mercaptan is 75.1%, the service life of the composite catalyst is 5.5h, compared with comparative example 1, the product selectivity is improved by 4.39%, and the service life of the composite catalyst is 0.5h shorter than that of an unmodified catalyst. Compared with comparative example 2, the product selectivity is improved by 3.32%, and the service life of the catalyst is shorter than that of the unmodified catalyst by 1.5 h.

Claims (7)

1. A method for preparing methyl mercaptan by extracting an aluminum modified composite catalyst from phosphogypsum is characterized by comprising the following steps:
step one, preparation of composite catalyst
Step 1.1: acid leaching of waste gypsum: adding dilute hydrochloric acid into the dried waste gypsum powder according to the liquid-solid ratio of 20mL/g, stirring and leaching for 1h at the acid leaching temperature of 80 ℃, centrifuging, taking supernate, adding sodium hydroxide solution, carrying out solid-liquid separation, taking supernate, adding dilute hydrochloric acid until white precipitates are completely dissolved, evaporating and concentrating, cooling and crystallizing, and filtering to obtain AlCl3·6H2O solution;
step 1.2: gamma-Al2O3Preparation: according to the molar ratio of the raw materials, AlCl3·6H2CTAB ═ 12.9-13.2:1-3, cetyltrimethylammonium bromide CTAB was added to the AlCl prepared in step 1.13·6H2Dissolving in O solution under stirring, and pumping with peristaltic pump at 5 mL/min-1Pumping 3 mol. L-1The precipitant is added until the pH value of the solution system is 8-9, the mixture is continuously stirred for 30min, aged in water bath at the temperature of 80 ℃ for 3h, cooled to room temperature, filtered, washed, dried at the temperature of 80 ℃ for 6 h-12 h to prepare a pseudoboehmite sample, and roasted at the temperature of 600 ℃ for 3h to prepare the gamma-Al2O3A sample;
step 1.3: the gamma-Al prepared in the step 1.22O3Modifying ZSM-5 by using a sample to obtain a composite catalyst; the modification treatment method comprises the following steps: according to the molar ratio of Si to Al to TPAOH to H2Adding sodium metaaluminate into deionized water, sequentially adding tetrapropylammonium hydroxide TPAOH and ethyl orthosilicate under continuous stirring to prepare a ZSM-5 precursor mixed solution, aging for 8-24h, and adding gamma-Al2O3Adding the mixed solution and ZSM-5 according to the mass ratio of 1-3:1-3, carrying out microwave hydrothermal reaction at 180 ℃ for 2h, cooling, filtering, washing, drying at 105-110 ℃ for 6 h-12 h, and roasting at 450-650 ℃ for 3h to obtain the gamma-Al after modification2O3@ ZSM-5 composite catalyst;
step two, preparation of methyl mercaptan:
step 2.1: loading the composite catalyst in the step 1.3 into a fixed bed catalyst tube, and introducing nitrogen and hydrogen sulfide gas into the fixed bed catalyst tube, wherein the reaction pressure is 0.5-1.0 MPa, and the reaction temperature is 330-420 ℃;
step 2.2: in a carrier gas of nitrogenUnder the action of the pressure sensor, a peristaltic pump is used for leading the prepared methanol solution to have the space velocity of 1.5h-1Conveying the methanol solution into a fixed bed catalyst tube, converting the methanol solution into methanol gas at high temperature, and fully contacting and reacting the hydrogen sulfide gas and the methanol gas with the catalyst to obtain a product methyl mercaptan, wherein the molar ratio of the hydrogen sulfide to the methanol gas is H2S:CH3OH＝2:1。
2. The method for preparing methyl mercaptan by extracting aluminum modified composite catalyst from phosphogypsum according to claim 1, wherein the concentration of dilute hydrochloric acid in the step 1.1 is 1 mol/L.
3. The method for preparing methyl mercaptan from modified composite catalyst extracted from aluminum by phosphogypsum as claimed in claim 1, wherein the gamma-Al in step 1.22O3The sample with 200 meshes is prepared by grinding and sieving.
4. The method for preparing methyl mercaptan from modified composite catalyst extracted from aluminum by phosphogypsum as claimed in claim 1, wherein the precipitant in step 1.2 is NH3·H2O、Na2CO3Or NaHCO3One kind of (1).
5. The method for preparing methyl mercaptan by using the ardealite extracted aluminum modified composite catalyst as claimed in claim 1, wherein in the modification treatment method in the step 1.3, the aging time is 12 hours.
6. The method for preparing methyl mercaptan from modified composite catalyst extracted from aluminum by phosphogypsum as claimed in claim 1, wherein the modification treatment method in step 1.3 is gamma-Al2O3The weight ratio of the active carbon to ZSM-5 is 1: 1.
7. The method for preparing methyl mercaptan from modified composite catalyst extracted from aluminum by phosphogypsum as claimed in claim 1, wherein in the modification treatment method in step 1.3, the roasting temperature is 550-600 ℃.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108246348A (en) * 2018-01-30 2018-07-06 贵州大学 A kind of preparation method of ZSM-5@γ-Al2O3 catalyst with core-casing structure

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108246348A (en) * 2018-01-30 2018-07-06 贵州大学 A kind of preparation method of ZSM-5@γ-Al2O3 catalyst with core-casing structure

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* Cited by examiner, † Cited by third party
Title
γ-Al2O3预处理方式对γ-Al2O3/SAPO-34复合催化剂物化性质及催化性能的影响;王冠超等;《人工晶体学报》;20180831;第47卷(第8期);第1535-1541页 *

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