Gas-phase dehydrochlorination of 1, 1, 2, 2-tetrachloroethane over the non-metal supported ionic liquid catalyst

Developing of non-metallic catalyst to replace metal catalyst is a meaningful and challenging direction.In this work,the non-metallic catalyst was synthetized successfully by loading ionic liquid onto the silica surface,which was applied for the gas-phase dehydrochlorination of 1,1,2,2-tetrachloroethane.The 12%TPPC/SiO2(wt%)showed the best results with the conversion of 1,1,2,2-tetrachloroethane reaching 100%.The selectivity of 1,1,2-trichloroethylene was 100%,and no deactivation was found during the evaluation period.The catalytic mechanism was investigated and possible reaction route was given,which was a reference for fabricating and design of solid base catalyst.

Phosphorus and nitrogen co-doped graphene for catalytic dehydrochlorination of 1,2-dichloroethane

A phosphorus and nitrogen co-doped graphene(PNG)was developed via a two-step pyrolysis approach through the intermedium of g-C_(3)N_(4) template and glyphosate as the phosphorus source,and was used for the catalytic dehydrochlorination of 1,2-dichloroethane(EDC)to vinyl chloride monomer(VCM)production.The characterization results indicate that a volcano relationship of surface area and surface properties with the usage of phosphorus precursor was observed,and the sample of PNG-900-6 possesses not only the thin film structure with enhanced surface area but also the smaller grain size of PNG attachments.Accordingly,such PNGs show a great improvement of catalytic performance in the dehydrochlorination of EDC,and the PNG-900-6 catalyst behaves the best with a 4-times higher activity than that on the nitrogen doped graphene(NG).It was also proved that the synergetic effect of the unique P-C coordination on the graphene to generate more quaternary nitrogen species was crucial in determining the catalytic performance of EDC conversion.Our results demonstrate that the phosphorus and nitrogen co-doped graphene offers many advantages in physical structure and chemical property,and are also great potential on the catalytic application in the dehydrochlorination of 1,2-dichloroethane.

ENVIRONMENTAL STABILITY OF THE POLYENE PREPARED BY DEHYDROCHLORINATION OF POLY(VINYL CHLORIDE)

A high-quality polyene can be obtained by exensive dehydrochlorination of poly(vinyl chloride) (PVC) in aliquid/solid two-phase system. The liquid phase is a tetrahydrofuran solution of PVC containing a small amount ofpoly(ethylene glycol) with molar mass of 400 g as a phase transfer catalys. The solid phase is potassium hydroxide particles.The structure of the polyene is polyacetylene-like and has a long conjugated C=C sequence and a narrow dispersity ofpolyene sequences according to its FT-infrared and Raman spectra. The environmental stability of the polyene was alsostudied by IR, Raman spectra and elemental analysis. Experimental results demonstrated that the polyene was susceptible toair and could be changed into a material containing high concentrations of hydroxyl and carbonyl groups. The polyenesequences were shortened and its dispersity became broader due to the effect of dioxygen.

Dehydrochlorination of Poly vinyl chloride Catalyzed by Quarternary Ammonium Salts in Solid Phase

The development of conducting polymers has been an active subject in the world since the late in 1970’s. The preparation of polyaeetylene-like polymers by dehydroehlorination of polyvinylchloride (PVC) is a very economical and useful procedure and,hence, a focus of enormous interest of both theoretieians and experimentalists. In recent years, many methods for dehydrochlorination of PVC in solution have been studied widely and many kinds of catalytic mechanisms have been suggested.

Highly efficient catalyst for 1,1,2-trichloroethane dehydrochlorination via BN_(3) frustrated Lewis acid-base pairs

In this study,a novel non-metallic carbon-based catalyst co-doped with boron and nitrogen(B,N)was successfully synthesized.By precisely controlling the carbonization temperature of a binary mixed ionic liquid,we selectively modified the doping site structure,ultimately constructing a B,N co-doped frustrated Lewis acid-base pair catalyst.This catalyst exhibited remarkable catalytic activity,selectivity,and stability in the dehydrochlorination reaction of 1,1,2-trichloroethane(TCE).Detailed characterization and theoretical calculations revealed that the primary active center of this catalyst was the BN_(3)configuration.Compared to conventional graphitic N structures,the BN_(3)structure had a higher p-band center,ensuring superior adsorption and activation capabilities for TCE during the reaction.Within the BN_(3)site,three negatively charged nitrogen atoms acted as Lewis bases,while positively charged boron atoms acted as Lewis acids.This synergistic interaction facilitated the specific dissociation of chlorine and hydrogen atoms from TCE,significantly enhancing the 1,1-dichloroethene selectivity.Through this research,we not only explored the active site structure and catalytic mechanism of B,N co-doped catalysts in depth but also provided an efficient,selective,and stable catalyst for the dehydrochlorination of TCE,contributing significantly to the development of non-metallic catalysts.

Rare Earth Stearates as Thermal Stabilizers for Rigid Poly(vinyl chloride)

A series of stearates with different rare-earth ion were investigated as thermal stabilizers for rigid PVC at 180 ℃ in air. Their stabilizing efficiency was based on measuring the rate of dehydrochlorination. The resulted revealed the higher stabilizing efficiency of the investigated rare-earth stearates as thermal stabilizers for rigid PVC compared with the thermal stabilizers for industry: calcium stearate, zinc stearate, butyl stannum mercaptide, phosphite esters, β-diketone and epoxidized sunflower oil. This was well illustrated by longer incubation period (T_S) values and lower rate of dehydrochlorination. The stable efficiency was affected by the nature of rare-earth element's individual electronic shell. The mechanism for the stabilizing effect of rare-earth stearates was proposed. The result was experimentally proved based on IR spectrum.

M/C_(3)N_(4)/AC(M=Au,Pt,Ru)‐catalyzed acetylene coupling with ethylene dichloride:How effective are the bifunctionalities?

Acetylene coupling with ethylene dichloride,which uses both coal and oil resources,is attractive for sustainable PVC manufacturing.Herein,highly active and stable carbon nitride‐based catalysts were developed by a novel pre‐oxidation‐pyrolysis process,affording unprecedented dehydrochlorination activity with good durability.The best‐performing system was further modified with different precious metals(Au,Pt,and Ru)to promote the hydrochlorination chemistry between the in‐situ formed hydrogen chloride and acetylene co‐feed.The presence of metal centers intensifies the hydrochlorination activity but weakens the dehydrochlorination ability due to competitive adsorption between the two reactants at the metal sites.Superior coupling performance was achieved over C_(3)N_(4)/AC and single‐atom Au/C_(3)N_(4)/AC catalysts in cascade reactors.Our results strongly suggest that dehydrochlorination is an essential step in the coupling reaction,and the activation of acetylene and ethylene dichloride molecules requires different active sites that should be engineered in future work.

Eco-friendly Technologies for Physical and Chemical Recycling of PVC-Related Wasteful Resources

The aim of this study is to enhance the recycled PVC （polyvinyl chloride） related material property by formulation technology and develop the recycling product processing technology furthermore develop the chemical recycling technology for last stage of PVC wastes. The formulation technology is composed of pre-treatment （crushing, separation etc.） and post-treatment （material ratio, additives, stabilizer etc.） to enhance the recyclate property. The formulation for recycled PVC by application basis and processing technology is applied to produce the structural product for civil and construction application such as pipe fittings and water drainage cap for environmental waterway. Also chemical recycling technology for end life PVC scrap which causes environmental pollution by incineration or landfill is studied for producing hydrocarbon and hydrogen chloride for VCM.

The Synthesis of Soluble Copolymer of Poly(p-Phenylene Vinylene)

Appling the dehydrochlorination reaction, the copolymerization of 1, 4-bis(chloromethyl)-2, 5-dimethyl benzene and 1, 4-bis(chloromethyl)-2-methoxy-5-hexyloxyl benzene was studied. The solubility of the copolymer was determined by the structure and molar ratio of two monomers. The structure of the copolymer was identified by UV, IR, and H-1 NMR analyses.

The Synthesis and Electronic Characteristics of Poly(p-Phenylene Vinylene) Derivatives

A series of soluble poly(p-phenylene vinylene) (PPV) derivatives were synthesized through dehydrochlorination with the p-metaoxy phenol as starting materials. The electronic characteristics of PPV derivatives were studied.

Highly Selective Gas-phase Synthesis of 1,1-Dichloroethylene from 1,1,2-Trichloroethane over Supported Amine Catalysts

The manufacture of 1,1-dichloroethylene（1,1-DCE） usually employs liquid phase method to perform the dehydrochlorination of 1,1,2-trichloroethane（TCE）, where large amounts of high-concentration salty wastewater is produced inevitably. It has been a long-term goal to achieve the gas phase synthesis of 1,1-DCE via supported cata- lysts. In this work, the gas-phase synthesis of 1,1-DCE from TCE was studied in the presence of pentaethylenehexamine（PEHA） supported on silica. High and stable selectivity to 1,1-DCE（up to 98%） was obtained, which could be ascribed to the relatively strong basicity of PEHA according to a proposed E2 mechanism. The formation of PEHA chloride from the HCI generated in situ was detected and was considered to be the main reason for the deactivation of PEHA catalyst.