Method for preparing aromatic hydrocarbon with carbon dioxide hydrogenation

Patent metadata

Field	Value
Publication number	US-10464859-B2
Application number	US-201716085397-A
Country	US
Kind code	B2
Filing date	Jul 25, 2017
Priority date	Sep 19, 2016
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

A method for preparing aromatic hydrocarbons with carbon dioxide hydrogenation, comprising: directly converting a mixed gas consisting of carbon dioxide and hydrogen with the catalysis of a composite catalyst under reaction conditions of a temperature of 250-450° C., a pressure of 0.01-10.0 MPa, a feedstock gas hourly space velocity of 500-50000 mL/(h·gcat) and a H2/CO2 molar ratio of 0.5-8.0, to produce aromatic hydrocarbons. The composite catalyst is a mixture of a first component and a second component. The first component is an iron-based catalyst for making low-carbon olefin via carbon dioxide hydrogenation, and the second component is at least one of metal modified or non-modified molecular sieves which are mainly used for olefin aromatization. In the method, CO2 conversion per pass may be above 33%, the hydrocarbon product selectivity may be controlled to be above 80%, the methane content is lower than 8%, C5+ hydrocarbon content is higher than 65% and the proportion of the aromatic hydrocarbons in C5+ hydrocarbons may be above 63%.

First claim

We claim:

1. A method for preparing aromatic hydrocarbon with carbon dioxide hydrogenation comprising: directly converting a mixed gas which comprises carbon dioxide and hydrogen, used as feed gas, with the catalysis of a composite catalyst to produce aromatic hydrocarbons,
wherein the composite catalyst is a mixture of a first component and a second component, the first component is an iron-based catalyst for making low-carbon olefin via carbon dioxide hydrogenation, and the second component is at least one of metal modified or non-modified molecular sieves which are mainly used for olefin aromatization; and the mass ratio of the first component to the second component is 1:10-10:1;
the iron-based catalyst comprises one or more of FeO, Fe 2 O 3 and Fe 3 O 4 as at least one main active component and optionally an auxiliary;
the iron-based catalyst has reverse water gas conversion function and olefin production function with CO hydrogenation;
the auxiliary is an oxide, and the content of the auxiliary is 0-20% of the total mass of the iron-based catalyst; and
the second component is a molecular sieve containing ten-membered ring porous structure.

2. The method according to claim 1 wherein the iron-based catalyst comprises Fe 3 O 4 as an active component, and the method comprises one of the following processes to make the iron-based catalyst:
A. the catalyst is prepared by a one-step synthesis method which comprises the following steps:
(1) mixing soluble Fe (II) salt and soluble Fe (III) salt to form a salt solution or mixing soluble Fe (II) salt, soluble Fe (III) salt and auxiliary salt to form a salt solution in accordance with a catalyst composition ratio, the concentration of Fe (III) in the salt solution being 0.02-0.8 mol/L; adding HCl solution with a concentration of 3-12.1 mol/L; regulating a pH value to 0-3, wherein the molar ratio of Fe(III) to Fe(II) in the salt solution is 2:(0.8-2.8); wherein the soluble Fe (II) salt and the soluble Fe (III) salt are water-soluble salt compounds; and the auxiliary salt is a water-soluble salt compound;
(2) adding aqueous alkali to (1); gradually regulating the pH value of the solution to 0-3 until the alkaline pH value is 9-12; after completing dripping, ageing for 1-10 h, wherein the aqueous alkali is an alkali solution with an adjustable pH value; the concentration of the aqueous alkali is 0.1-8 mol/L, wherein R refers to an organo-functional group and comprises C 1 -C 20 alkyl, C 1 -C 20 alkenyl or C 6 -C 20 aryl;
(3) after completing the reaction, separating deposited products from (2) through magnetic field absorption, centrifugal or sucking filtration method; adequately washing the deposited products with deionized water, drying, optionally roasting at a roasting temperature of 200-600° C. for a roasting time of 2-10 h, to prepare the iron-based catalyst containing the auxiliary;
B. or the catalyst is prepared by a one-step synthesis method which comprises the following steps:
(1) mixing soluble Fe (II) salt and soluble Fe (III) salt to form a salt solution in accordance with a catalyst composition ratio, the concentration of Fe (III) in the salt solution being 0.02-0.8 mol/L; adding HCl solution with a concentration of 3-12.1 mol/L; and regulating a pH value to 0-3, wherein the molar ratio of Fe(III) to Fe(II) in the salt solution is 2:(0.8-2.8);
(2) adding aqueous alkali containing Na or K in A method to (1); gradually regulating the pH value of the solution to 0-3 until the alkaline pH value is 9-12; and after completing dripping, ageing for 1-10 h;
(3) after completing the reaction, separating deposited products from (2) through magnetic field absorption, centrifugal or sucking filtration method; washing the deposited products with deionized water; controlling the content of remaining Na or K in the catalyst by controlling washing times and water consumption per washing; drying, roasting or not roasting at a roasting temperature of 200-600° C. for a roasting time of 2-10 h, to prepare the iron-based catalyst containing the auxiliary;
C. or the catalyst is prepared by synthesizing Fe 3 O 4 through a coprecipitation method and adding the auxiliary through an immersion method, comprising the following steps:
(1) mixing soluble Fe (II) salt and soluble Fe (III) salt to form a salt solution in accordance with a catalyst composition ratio, the concentration of Fe (III) in the salt solution being 0.02-0.8 mol/L; adding HCl solution with a concentration of 3-12.1 mol/L; and regulating a pH value to 0-3, wherein the molar ratio of Fe(III) to Fe(II) in the salt solution is 2:(0.8-2.8);
(2) adding the aqueous alkali in A method to (1); gradually regulating the pH value of the solution to 0-3 until the alkaline pH value is 9-12; and after completing dripping, ageing for 1-10 h;
(3) after completing the reaction, separating deposited products from (2) through magnetic field absorption, centrifugal or sucking filtration method; adequately washing the deposited products with deionized water, and drying, to prepare the active component Fe 3 O 4 ;
(4) combining the auxiliary salt with the active component through the immersion method to form a catalyst, which comprises: computing the amount of theoretically required auxiliary salt according to the required auxiliary content to prepare an aqueous solution of the auxiliary salt; immersing equal volume of Fe 3 O 4 obtained in preparation of (3) into the solution; stirring, standing, drying and roasting at a roasting temperature of 200-600° C. for a roasting time of 2-10 h, to prepare the iron-based catalyst containing the auxiliary.

3. The method according to claim 1 , wherein during modification of the molecular sieve, the metal component is supported by the molecular sieve through one of the following two methods:
(1) preparing through an isometric immersion method, which comprises: computing the amount of theoretically required metal salt according to the required metal content to prepare an aqueous solution of the metal salt, wherein the metal salt is selected from the group consisting of: nitrate, chloride, bromide, acetate, acetylacetonate, citrate, oxalate and benzoate; immersing equal volume of molecular sieve that needs modification treatment into the solution; stirring, standing, drying and roasting at a roasting temperature of 300-700° C. for a roasting time of 2-10 h, to prepare a metal modified molecular sieve;
(2) preparing through an ion exchange method, which comprises: computing the amount of theoretically required metal salt according to the required metal content to prepare an aqueous solution of the metal salt, wherein the metal salt is selected from the group consisting of: nitrate, chloride, bromide, acetate, acetylacetonate, citrate, oxalate and benzoate; mixing the molecular sieve that needs modification treatment with a mass ratio of solid to liquid of 1:(10-200); conducting ion exchange for 2-24 h; and washing, drying and roasting at a roasting temperature of 300-700° C. for a roasting time of 2-10 h, to prepare a metal modified molecular sieve.

4. The method according to claim 1 comprising mixing the two components of the composite catalyst through one of the following two modes:
(1) particle mixing mode: respectively weighing iron-based catalyst and molecular sieve catalyst powder; respectively tableting, shaping and screening; and uniformly mixing particles according to a required mass ratio to form a composite catalyst;
(2) layered packing mode: successively packing required mass of the iron-based catalyst and the molecular sieve catalyst on catalyst bed layers in a top-to-bottom sequence of reactors, wherein two catalyst bed layer components contain or do not contain an isolation layer of inert material, and the mass ratio of the isolation layer of inert material to the active component of the composit

Assignees

• Dalian Inst Chem & Physics Cas

Inventors

• Ge Qingjie
• Wei Jian
• Xu Hengyong

Classifications

• B01J29/7684

  TON-type, e.g. Theta-1, ISI-1, KZ-2, NU-10 or ZSM-22 · CPC title

• B01J37/04

  Mixing {(B01J37/0009, B01J37/0018 take precedence)} · CPC title

• C07C15/073

  Ethylbenzene · CPC title

• C07C2523/745

  Iron · CPC title

• B01J37/088

  Decomposition of a metal salt · CPC title