CN102911007B - Mercury-free synthetic method of chloroethylene - Google Patents

Abstract

A mercury-free synthesis method of vinyl chloride relates to a vinyl chloride. A mercury-free synthesis method of vinyl chloride which enables energy to be comprehensively utilized is provided. 1) Mix at least one of hydrogen chloride or ethylene dichloride vapor with acetylene as a raw material to obtain a mixed raw material gas; 2) After preheating the mixed raw material gas, pass it into a catalyst-loaded tube reactor for reaction; 3) Control the flow rate of the raw material mixture, adjust the pressure of the reaction system, so that the conversion rate of at least one gas in the raw material mixture reaches more than 80%; 4) compress, freeze, separate and rectify the reaction product obtained in step 3), Vinyl chloride monomers that meet the polymerization requirements can be obtained. It can not only solve the problem of mercury pollution in the vinyl chloride industry, but also by-produce steam to save energy and reduce consumption. At the same time, due to the use of the tubular cooling system, the hot spot temperature of the catalytic bed can be controlled within a small range, which is conducive to the long-term stable operation of the catalyst.

Description

A kind of mercury-free synthetic method of vinyl chloride

technical field

The invention relates to vinyl chloride, in particular to a mercury-free synthesis method of vinyl chloride.

Background technique

Polyvinyl chloride (PVC) is one of the five general-purpose plastics, and its output is second only to polyethylene (PE), ranking second in the world's plastic output, with an annual output of more than 40 million tons.

The earliest synthesis method of polyvinyl chloride is the acetylene method, that is, under the catalysis of mercuric chloride, acetylene and hydrogen chloride are added to synthesize vinyl chloride, and vinyl chloride is polymerized to obtain polyvinyl chloride. Due to the use of mercuric chloride as a catalyst in this method, there is a serious problem of mercury pollution. After the process of producing ethylene from petroleum cracking matured, foreign countries switched to ethylene to produce vinyl chloride, and in the 1980s, the process of producing vinyl chloride from acetylene was basically eliminated. Due to the shortage of ethylene resources and abundant calcium carbide resources in my country, the production of PVC is still dominated by the acetylene process. However, with the continuous expansion of the production capacity of the acetylene method, it is facing huge pressure of environmental pollution. Domestic counterparts have been devoting themselves to the research of mercury-free catalysts in recent years, and have made certain achievements.

In the Chinese patent application with the application number 201010149180.1, a new method for the preparation of vinyl chloride is provided. This method uses barium chloride as a catalyst to prepare vinyl chloride by catalytic reforming of acetylene dichloroethane, which is a pioneer for mercury-free catalysis. a new way.

In the Chinese patent application with application number 201110330158.1 (international patent application number PCT/CN2011/081317), a method for preparing a catalyst for preparing vinyl chloride from acetylene dichloroethane is provided. The catalyst prepared by this method can not only catalyze acetylene dichloroethane to prepare vinyl chloride, but also catalyze acetylene hydrogen chloride to synthesize vinyl chloride, which can meet the industrial requirements of acetylene and hydrogen chloride, acetylene and dichloroethane to catalyze the synthesis of vinyl chloride, and is a non- Mercury-catalyzed synthesis of vinyl chloride opens up a new route.

In the synthesis process of vinyl chloride, because the mechanical strength of activated carbon is difficult to meet the requirements of fluidized bed, the reactor usually adopts fixed bed reactor. Since the reaction generates a large amount of heat, the temperature of the catalytic bed is likely to rise rapidly, resulting in a phenomenon of overheating, and the reaction bed needs to be cooled, so the reactor adopts a tubular reactor.

In the traditional synthesis process, due to the low sublimation temperature of mercuric chloride, the temperature of the reaction bed must be controlled within 180°C, and the temperature of the cooling water must be controlled below 100°C, resulting in the need for a large amount of water for cooling.

Contents of the invention

The object of the present invention is to provide a mercury-free synthesis method of vinyl chloride which can comprehensively utilize energy to solve the problems existing in the existing vinyl chloride synthesis method.

The present invention comprises the following steps:

1) Mix at least one of hydrogen chloride or ethylene dichloride vapor with acetylene as a raw material to obtain a mixed raw material gas;

2) After preheating the mixed raw material gas, it is passed into the column and tube reactor loaded with catalyst for reaction;

3) Control the flow rate of the raw material mixture, adjust the pressure of the reaction system, and make the conversion rate of at least one gas in the raw material mixture reach more than 80%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

In step 1), the molar ratio of hydrogen chloride or ethylene dichloride vapor to acetylene may be (0.7-1.3):1.

In step 2), the preheating temperature is preferably controlled at 100-180°C; the catalyst can be selected from carbon-supported barium salt catalyst, and the specific steps of the preparation method of the carbon-supported barium salt catalyst are as follows (see The method disclosed in Chinese patent 201110330158.1):

Water-soluble compounds of barium, water-soluble compounds of phosphorus and water-based polymer monomers are added with water to form a solution or emulsion A; activated carbon is added to the solution or emulsion A for soaking; the soaked activated carbon is taken out, dried, and then Polymerize the monomer; heat and dehydrate the polymerized activated carbon, decompose and carbonize the polymer; activate the carbonized catalyst to obtain a catalyst for the preparation of vinyl chloride.

The conditions of the reaction can be: water is used as cooling medium, and the temperature of the reaction bed is controlled to be 130-250°C, preferably 150-230°C;

In step 3), the space velocity of the mixed feed gas may be 20-100/h; the gauge pressure of the reaction system may be 0-0.2 MPa.

In the present invention, since the activity temperature of the barium chloride catalyst is relatively high, and the temperature adaptability range is wider, the temperature of the cooling water can be controlled above 100°C, and the heat of reaction is taken away by the latent heat of vaporization of water, so that the heat exchange efficiency is high, At the same time, steam can be produced by-product, so that the energy can be comprehensively utilized.

The invention can not only solve the problem of mercury pollution in the vinyl chloride industry, but also can by-produce steam to save energy and reduce consumption. At the same time, due to the use of the tubular cooling system, the hot spot temperature of the catalytic bed can be controlled within a small range, which is conducive to the long-term stable operation of the catalyst.

Detailed ways

The following examples will further illustrate the present invention.

Example 1

1) Mix hydrogen chloride and acetylene as raw materials, and control the molar ratio of hydrogen chloride and acetylene to 1:1 to obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 100°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 130°C;

3) Control the space velocity of the raw material mixture to 20/h, adjust the gauge pressure of the reaction system to 0.2MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 80%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 2

1) Mix hydrogen chloride and acetylene as raw materials, and adjust the molar ratio of hydrogen chloride and acetylene to 1.3:1 to obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 120°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed to 150°C;

3) Control the space velocity of the raw material mixture to 40/h, adjust the gauge pressure of the reaction system to 0.15MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 85%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 3

1) Mix hydrogen chloride and acetylene as raw materials, and adjust the molar ratio of hydrogen chloride and acetylene to 0.7:1 to obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 140°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 180°C;

3) Control the space velocity of the raw material mixed gas to 60/h, adjust the gauge pressure of the reaction system to 0.1MPa, and analyze by gas chromatography, the conversion rate of hydrogen chloride reaches 90%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 4

1) Mix hydrogen chloride and acetylene as raw materials, and the molar ratio of hydrogen chloride and acetylene is 1.1:1 to obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 150°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 180°C;

3) Control the space velocity of the raw material mixture to 50/h, adjust the gauge pressure of the reaction system to 0.5MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 95%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 5

1) Mix hydrogen chloride and acetylene as raw materials, and the molar ratio of hydrogen chloride and acetylene is 1.05:1 to obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 160°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 220°C;

3) Control the space velocity of the raw material mixture to 100/h, adjust the gauge pressure of the reaction system to normal pressure, and analyze by gas chromatography, the conversion rate of acetylene reaches 95%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 6

1) Using hydrogen chloride, dichloroethane steam and acetylene as raw materials, the molar ratio of hydrogen chloride, dichloroethane and acetylene is 0.7:0.3:1 to obtain a mixed raw material gas;

2) After preheating the mixed raw material gas to 150°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 210°C;

3) Control the space velocity of the raw material mixture to 70/h, adjust the gauge pressure of the reaction system to 0.08MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 80%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 7

1) Using hydrogen chloride, dichloroethane steam and acetylene as raw materials, the molar ratio of hydrogen chloride, dichloroethane, and acetylene is 0.5:0.5:1 to obtain a mixed raw material gas;

2) After preheating the mixed raw material gas to 170°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 230°C;

3) Control the space velocity of the raw material mixture to 60/h, adjust the gauge pressure of the reaction system to 0.1MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 85%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Example 8

1) Mix dichloroethane steam and acetylene as raw materials, adjust the molar ratio of dichloroethane and acetylene to 1:1, and obtain mixed raw material gas;

2) After preheating the mixed raw material gas to 180°C, pass it into the tube reactor loaded with carbon-supported barium salt catalyst for reaction, use water as the cooling medium, and control the temperature of the reaction bed at 250°C;

3) Control the space velocity of the raw material mixture to 40/h, adjust the gauge pressure of the reaction system to 0.12MPa, and analyze by gas chromatography, the conversion rate of acetylene reaches 90%;

4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the vinyl chloride monomer meeting the polymerization requirements.

Claims (6)

1. a mercury-free synthesis method of vinyl chloride is characterized in that comprising the following steps: 1) mixing at least one of hydrogen chloride or ethylene dichloride vapor with acetylene as a raw material to obtain a mixed raw material gas; the molar ratio of the hydrogen chloride or ethylene dichloride vapor to acetylene is (0.7～1.3): 1; 2) After the mixed feed gas is preheated, it is passed into a catalyst-loaded tube reactor to react; the catalyst is selected from carbon-supported barium salt catalysts, and the specific steps of the preparation method of the carbon-supported barium salt catalysts are as follows: Water-soluble compounds of barium, water-soluble compounds of phosphorus, and water-based polymer monomers are added with water to form a solution or emulsion A; activated carbon is added to the solution or emulsion A for soaking; the soaked activated carbon is taken out, dried, and then Polymerize the monomer; heat and dehydrate the polymerized activated carbon, and decompose and carbonize the polymer; activate the carbonized catalyst to obtain a catalyst for the preparation of vinyl chloride; 3) controlling the flow rate of the raw material mixture, adjusting the pressure of the reaction system, so that the conversion rate of at least one gas in the raw material mixture reaches more than 80%; 4) The reaction product obtained in step 3) is compressed, frozen, separated and rectified to obtain the product vinyl chloride monomer meeting the polymerization requirements. 2. A mercury-free synthesis method of vinyl chloride as claimed in claim 1, characterized in that in step 2), the temperature of the preheating is controlled at 100-180°C. 3. The mercury-free synthetic method of a kind of vinyl chloride as claimed in claim 1, it is characterized in that in step 2), the condition of described reaction is: use water as cooling medium, the temperature of control reaction bed is 130～250 ℃ . 4. A mercury-free synthesis method of vinyl chloride as claimed in claim 3, characterized in that the temperature of the controlled reaction bed is 150-230°C. 5. A mercury-free synthesis method of vinyl chloride as claimed in claim 1, characterized in that in step 3), the space velocity of the mixed feed gas is 20-100/h. 6. A mercury-free synthesis method of vinyl chloride as claimed in claim 1, characterized in that in step 3), the gauge pressure of the reaction system is 0-0.2 MPa.