Method for catalytic dehydration of glycerol to acrolein

Patent metadata

Field	Value
Publication number	US-9926253-B2
Application number	US-201715605915-A
Country	US
Kind code	B2
Filing date	May 25, 2017
Priority date	May 30, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A novel method for catalytic dehydration of glycerol to acrolein is provided. A fixed bed reactor is used, which is placed in a microwave unit. The feedstock is introduced into the fixed bed reactor after being preheated and gasified. Continuous glycerol dehydration occurs in the presence of a microwave-absorbing catalyst in the fixed bed reactor to form acrolein. The microwave-absorbing catalyst is composed of an active component loaded on a core-shell structure which consists of microwave absorbent coated by an oxide. The uniformity of microwave heating can reduce the formation of hot spot during the reaction and hence improve the catalyst stability. The process and operation is simple, and the unit can steadily run for a long time.

First claim

What is claimed is:

1. A method for catalytic dehydration of glycerol to acrolein, wherein:
a glycerol used as raw material is introduced into a fixed bed reactor after being preheated and gasified in a preheater,
the gasified glycerol is then continuously dehydrated to form acrolein in the presence of a microwave-absorbing catalyst in the fixed bed reactor under microwaves generated by a microwave generator.

2. The method according to claim 1 , wherein the microwave-absorbing catalyst is denoted as A-M x O y @MA, in which:
A represents an active component of the microwave-absorbing catalyst, M x O y represents a coating material, MA represents a microwave absorbent, and the microwave absorbent is coated by the coating material to form a catalyst support of the microwave-absorbing catalyst, denoted as M x O y @MA.

3. The method according to claim 1 , wherein the glycerol used is in an aqueous solution with concentration of 10-60 wt %, and the glycerol is preheated and gasified at a temperature of 200-300° C., and the glycerol is dehydrated at a temperature of 250-350° C.

4. The method according to claim 2 , wherein the active component of the microwave-absorbing catalyst is any one of metal oxide, heteropoly acid, phosphate, or sulfate, with a loading amount of 4-20 wt %; the coating material is oxide, with a coating amount of 25-75 wt %; the microwave absorbent is any one of silicon carbide, activated carbon, graphite, or single crystal silicon.

5. The method according to claim 4 , wherein the oxide used as the coating material is zirconium oxide, aluminum oxide, silicon dioxide or titanium oxide.

6. The method according to claim 1 , wherein the fixed bed reactor is connected with an inlet and an outlet, with a catalyst bed placed at a center of the fixed bed reactor, and the fixed bed reactor is made of a material at is microwave transmitting and high temperature resistance.

7. The method according to claim 6 , wherein the material that is microwave transmitting and high temperature resistance is glass or ceramics.

8. The method according to claim 1 , wherein the microwave generator is connected with a temperature controller, a paperless recorder, and an infrared sensor ( 5 ) successively, the infrared sensor is used to accurately measure a temperature of a catalyst bed in the fixed bed reactor, and a measured data is transmitted to the temperature controller through the paperless recorder; when the temperature reaches a set point, the microwave generator is controlled to be on or off by the temperature controller.

9. The method according to claim 2 , wherein a process for preparing the microwave-absorbing catalyst is as follows:
1) to prepare the catalyst support M x O y @MA, the microwave absorbent is first dispersed in a water bath at 60° C. and being mixed with a dispersant to form a solution, a precursor of the coating material is then added into the solution, followed by addition of ammonia and keeping a pH of the solution stable, the added precursor is hydrolyzed so as to form the coating material that is coated onto the microwave absorbent, after completion of reaction, the solution is filtered, washed, dried, and calcined to form the catalyst support of the microwave-absorbing catalyst M x O y @MA, wherein the precursor of the coating material is compounds containing zirconium, aluminum, silicon, or titanium, which can be hydrolyzed to form the coating material such as zirconium oxide, aluminum oxide, silicon dioxide or titanium oxide;
2) the active component or a precursor of the active component is dissolved in water, and then added to the solution of the catalyst support of the microwave-absorbing catalyst prepared in step 1) for impregnation, after complete impregnation, the impregnated solution is dried, calcined, squashed, and sieved to obtain the microwave-absorbing catalyst.

10. The method according to claim 9 , wherein the dispersant is sodium metasilicate or tetramethyl ammonium hydroxide.

Assignees

• Univ Zhejiang Technology

Inventors

• Nie Yong
• Xie Qinglong
• Gong Ruchao
• Duan Ying
• Li Shanshan
• Liu Yang
• Liang Xiaojiang
• Wu Zhenyu
• Lu Meizhen
• Yu Fengwen
• Ji Jianbing

Classifications

• C07C45/002 Primary

  by dehydrogenation · CPC title

• B01J35/002

  Operations & Transport · mapped topic

• B01J23/30

  Tungsten · CPC title

• B01J27/188 Primary

  with chromium, molybdenum, tungsten or polonium · CPC title

• C07C45/52 Primary

  by dehydration and rearrangement involving two hydroxy groups in the same molecule · CPC title