阅读说明：本技术 一种四氯化碳气相加氢转化制氯仿的改进工艺 (Improved process for preparing chloroform by carbon tetrachloride gas-phase hydrogenation conversion ) 是由 徐成华 刘建英 田黎霞 杨皓 王娟芸 于 2019-09-26 设计创作，主要内容包括：本发明公告了一种四氯化碳气相加氢转化制氯仿的改进工艺,液体四氯化碳加热气化,进转化反应器原料气总组分为氢气：四氯化碳=4~7：1,甲烷：四氯化碳=1~7：1,氯化氢≤1%；反应器产物冷冻分离氯化物后,送变压吸附分离装置脱除氯化氢到≤1%,其它气相产物直接增压送入反应器循环使用,当反应产物中甲烷浓度超过25~37%后,分离脱除多余的甲烷,由此提高四氯化碳加氢转化制氯仿的氢气有效利用率达到95%以上,甲烷收率大幅降低。(The invention discloses an improved process for preparing chloroform by gas-phase hydroconversion of carbon tetrachloride, which comprises the steps of heating and gasifying liquid carbon tetrachloride, wherein the total composition of raw material gas entering a conversion reactor comprises hydrogen, namely carbon tetrachloride =4 ~ 7: 1, methane, namely carbon tetrachloride =1 ~ 7: 1, and hydrogen chloride is less than or equal to 1 percent, after a product of the reactor is frozen and separated from chlorides, the hydrogen chloride is removed to be less than or equal to 1 percent by a pressure swing adsorption separation device, other gas-phase products are directly pressurized and sent to the reactor for recycling, and when the concentration of methane in the reaction product exceeds 25 ~ 37 percent, redundant methane is separated and removed, so that the effective utilization rate of the hydrogen for preparing the chloroform by the hydroconversion of the carbon tetrachloride is improved to be.)

1. An improved process for preparing chloroform by gas-phase hydroconversion of carbon tetrachloride is characterized in that liquid carbon tetrachloride is heated and gasified, the total composition of raw material gas entering a conversion reactor is hydrogen with the weight ratio of carbon tetrachloride =4 ~ 7: 1, methane with the weight ratio of carbon tetrachloride =1 ~ 7: 1, and hydrogen chloride is less than or equal to 1%, after chloride is separated by freezing a product of the reactor, hydrogen chloride is removed to be less than or equal to 1% by a pressure swing adsorption separation device, other gas-phase products are directly pressurized and sent to the reactor for recycling, and when the concentration of methane in the reaction product exceeds 25 ~ 37%, redundant methane is separated and removed, so that the effective utilization rate of hydrogen for preparing chloroform by hydroconversion of carbon tetrachloride is improved to be more than 95%, and the yield.

Technical Field

The invention relates to the fields of organic synthesis, energy conservation and environmental protection, and discloses a method for effectively reducing the emission of gas wastes and reducing the resource consumption.

Background

CN110041162A of Yangxi Lishi culture engineering Co., Ltd discloses a green production process of methane chloride, which comprises a hydrochlorination process, a chlorination process, a refining process, a tail gas absorption process, a liquid chlorine vaporization process, a wastewater treatment process, a tail gas absorption and high-boiling-point substance incineration process and a carbon tetrachloride conversion process. The technology is adopted, and the methane chloride production process is improved through a methane chloride direct supply process, a methane chloride wastewater flash evaporation treatment system, alkali concentration optimization in a refined alkali washing process, recycling of chlorination reaction heat, a carbon tetrachloride-to-chloroform process and tail gas absorption and high-boiling-point substance incineration treatment, so that an energy-saving, green, safe and environment-friendly green production process is achieved, the production cost of enterprises is reduced, and the economic benefits of the enterprises are increased.

CN107876046A of Chengang, etc. of Jiangsu physical culture Limited company announced a high-efficiency catalyst for preparing chloroform by gas-phase hydrogenation and dechlorination of carbon tetrachloride, which is mainly characterized in that active component platinum is distributed on carrier alumina in a form of thick-shell permeation, the catalyst takes noble metal platinum as an active ingredient, the introduction amount of the platinum is 0.1 ~ percent of the total mass of the carrier, the carrier is spherical, strip-shaped or other alumina, the carrier is pretreated by organic acid competitive adsorbent, so that the active component platinum is distributed on the carrier in a form of thick-shell permeation.

Xuhua CN1701846A of Chengdu organic chemistry Limited company of Chinese academy of sciences, having high catalytic activity and stability and used for gas-phase catalytic hydrodechlorination of carbon tetrachloride fixed bed and containing Pt hollow Al₂O₃A catalyst. The catalyst is simultaneously introduced with metal ions which have a synergistic catalytic hydrodechlorination effect with platinum and chloride ions which are resistant to HCl poisoning, and is activated with air before the catalyst is reduced. The method of the invention can improve the activity and catalytic stability of the catalyst.

It can be seen from the bulletin documents that the primary conversion efficiency of carbon tetrachloride is more important to the industry, the comprehensive utilization of chloroform selectivity and the subsequent conversion tail gas is not important enough, and the utilization rate of hydrogen is not improved more effectively. The utilization rate of hydrogen is only about 10%.

Since hydrogen chloride has a toxic effect on a catalyst, the separation and purification of hydrogen by pressure swing adsorption is a feasible method, but hydrogen chloride and methane must be removed by 100% in the process of purifying hydrogen, so that the yield of hydrogen is lower than 60%, and the total use efficiency of hydrogen is only 46%.

The invention relates to an improved method for preventing the generation of methane by using hydrogenation tail gas, improving the conversion rate of carbon tetrachloride and improving the utilization efficiency of hydrogen.

Disclosure of Invention

An improved process for preparing chloroform by gas-phase hydroconversion of carbon tetrachloride comprises the steps of heating and gasifying liquid carbon tetrachloride, mixing the previous hydrogen with carbon tetrachloride =7 ~ 12: 1, and completely converting more than 99% by one-time catalytic hydrogenation, wherein the total composition of raw material gas of a conversion reactor comprises hydrogen with carbon tetrachloride =4 ~ 7: 1, methane with carbon tetrachloride =1 ~ 7: 1, and hydrogen chloride is less than or equal to 1%.

The hydrogen is expensive and is used as fuel gas, which is a high-value product and a low-value product.

The energy consumption of liquid phase rectification and separation is extremely low, the two consumption are compared, and the value of recycling hydrogen is far more than the rectification cost.

Detailed Description