Second-stage reaction process for preparing propenoic acid or ester from lactic acid or ester

Abstract

The invention relates to a two-section reaction method for preparing acrylic acid or propylene ester by lactic acid or lactic ester, belonging to the biological matrix chemical product field. A two-stage vertical type fixed bed reactor is adopted; a front part of an upper-section reactor is connected with a material carburetor; a lower-section reactor is connected with a gas-liquid separator; catalyzers A,B,C and D are adopted, wherein, the catalyzer A is an X-type molecular sieve; a NaY-type molecular sieve is roasted, subject to ion exchange by a potassium nitrate solution to prepare the catalyzer B; a nitrate solution and sodium phosphate are used to prepare phosphate as the catalyzer C; and a mixture of CaSO4 and CuSO4 and phosphate are mixed to prepare the catalyzer D; the catalyzer A or B is positioned in the upper-section reactor; the catalyzer C or D is positioned in the lower-section reactor; air in the reactors is exhausted by nitrogen; the nitrogen flow speed is between 5 and 100 ml / min; the temperature of the carburetor is 235 DEG C; the upper-section reaction temperature is between 275 and 350 DEG C; the lower-section reaction temperature is between 350 and 450 DEG C; and a condensed liquid of the gas-liquid separator is kept at a temperature of 2 DEG C; after the temperature is stabilized, raw material is pumped to the carburetor; the raw material is an aqueous solution of the ethyl lactate and the methyl lactate or a lactic acid aqueous solution added with a polymerization inhibitor of 0.5 percent of the raw material mass; and the sampling speed of the raw material is between 0.5 and 2 ml / h. The method develops the advantages of different catalyzers and improves the selectivity of a target product.

Description

technical field [0001] The invention belongs to the field of bio-based chemicals, and relates to the process of preparing acrylic acid or esters by catalytic dehydration of lactic acid or esters in a fixed-bed reactor. The experiment adopts the production method of a two-stage fixed-bed reactor. Background technique [0002] Acrylic acid is one of the important basic chemical raw materials. It is widely used in coatings, chemical fibers, textiles, light industry and other industries, as well as in oil exploration, oil additives and other fields. It is widely used and has a large market demand. The market demand has been showing an upward trend in recent years. Especially in Asia. [0003] At present, acrylic acid is basically synthesized from petrochemical products, most of which are produced by propylene oxidation. However, fossil resources are non-renewable. With the further aggravation of the global energy crisis, how to use renewable biological resources is becoming mor...

AI Technical Summary

Problems solved by technology

[0005] Previous studies have made some progress, but the selectivity of acrylic acid and esters is relatively low (hereinafter referred to as the total selectivity of acrylic acid and acrylates is selectivity)