Production process for refining dichlorohydrin by glycerol reaction distillation

Abstract

The invention provides a production process for preparing dichloropropanol by reactive distillation of glycerol. The production process comprises the following steps: the raw material glycerol containing a homogeneous catalyst is sent to a reactive rectification tower from the top after heat exchange, hydrogen chloride gas enters from the lower part of a rectification section of the tubular reactive rectification tower, and the raw material glycerol and countercurrent flow of the hydrogen chloride gas are subject to absorption and chlorination reaction by a packing layer at the temperature of 90-120 DEG C and the temperature of 0.001-0.1MPa (absolute pressure) and are rectified; omonochloropropylene glycol at the bottom of the tubular reactive rectification tower, glycerol and glycerol oligomer are sent to a heavy constituent separation tower for decompressing and recovering the monochloropropylene glycol and the glycerol is returned to the raw material glycerol; and product gas on the top of tubular reactive rectification tower is cooled by a heat exchanger to obtain the dichloropropanol which is sent to a cyclization working procedure, and tail gas is further washed with lye, and is discharged from by a vacuum pump.

Description

1. Technical Field [0001] The invention provides a production process for preparing dichloropropanol by reactive distillation of glycerin, which belongs to the field of fine chemicals. 2. Background technology [0002] At present, epichlorohydrin and its precursor dichloropropanol mainly have two production processes: propylene high temperature chlorination method, allyl alcohol method and glycerin chlorination method. The high-temperature chlorination of propylene has been the world’s main production method for epichlorohydrin and its precursor dichloropropanol. The production process is flexible, the process is mature, and the operation is stable, but there are high conversion rates, many by-products, and high energy consumption. Severe equipment corrosion, more waste water and slag, and higher and higher prices of propylene raw materials. The allyl alcohol method has mild reaction conditions, high yield, less by-products, and less sewage, but has many reaction steps, short cat...

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Problems solved by technology

[0003] The process of glycerin chlorination to produce dichloropropanol and epichlorohydrin developed by Jiangsu University of Technology is a batch method, which is prepared by using hydrogen chloride gas in a tank reactor. The investment is only a quarter of that of the propylene method, the cost is low, and the operating conditions are mild. , Safe and reliable, the waste water is only one-tenth of that of the propylene method, but the conversion rate is relatively low, the consumption of raw materials is large, the by-products are high, and the scale is difficult to expand

The published patents CN1882522A and CN1845888A are both produced by continuous method, and are all single or multi-stage series fully mixed bed reactors. The final reaction product is separated under normal pressure or reduced pressure, and the conversion rate, selectivity and yield are high, but the consumption of raw materials is relatively low. Large, high by-products, difficult to scale up

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