Study Of Biomass Based Carbon Catalyst For Acetylene Hydrochlorination To Synthesize Vinyl Chloride

Polyvinyl chloride?PVC?is a worldwide engineering plastic,and is called the five general-purpose resins together with polyethylene,polypropylene,polystyrene and polyacrylonitrile-butadiene-styrene.There are two ways to synthesize VCM in industrial production:acetylene hydrochlorination and ethylene oxychlorination.Due to the characteristic of China's resources rich in coal and lack of oil,VCM is most manufactured by acetylene hydrochlorination,which uses supported HgCl₂ as catalyst.However,the catalyst is highly volatile under high temperature,which seriously damages the ecological environment and hurt human health.Therefore,the development of China's coal-based PVC industry relies on the study of mercury-free catalysts.This paper mainly focuses on this problem,in which two kinds of cheap bio-carbon material catalysts are synthesized for acetylene hydrochlorination reaction.The proposed catalysts show excellent catalytic activity and stability,and have great potential as mercury-free for the industry of acetylene hydrochlorination in the future.The main contents are as follows:1.A simple“one-pot”process without adding any metal species is used to make bamboo-based biomass nitrogen-doped carbon catalyst,in which Bamboo-based biomass nitrogen-doped carbon?denoted as N-BC?is prepared by bamboo as precursor,ZnCl₂ as activator and acrylamide as nitrogen source.The catalyst is evaluated in acetylene hydrochlorination,and the preparation process is optimized.The effects of nitrogen doping amount,activation dose and calcination temperature on the catalytic activity of the catalyst are investigated.The N-BC catalyst delivers stable activity during a 50 hour test with acetylene conversion reaching 90-95%and vinyl chloride selectivity over 98%at 200?C,showing good catalytic activity and stability.We have carried out a series of material characterizations on the catalysts.The BET and SEM results show that N-BC has a special fiber-tubular physical structure,and a high specific surface area;EA,ICP,FT-IR and XPS results all show that nitrogen is successfully doped into the carbon skeleton,changing the electron transfer ability;XPS results show a high content of pyridinium nitrogen and oxygen-containing groups of N-BC;The TPD results strongly explain that the high activity of the N-BC catalyst is caused by the large amount of adsorption of the reactants.2.Based on the study of N-BC catalyst,the SBMCs catalysts are prepared with the high-nitrogen biomass of soybean meal as raw material,which is obtained from soybean oil,without any external nitrogen source.We optimize the activator and the consider effect of calcination temperature.The catalyst shows more outstanding performance,which is obtained by using ZnCl₂ as the activator,the amount of soybean meal is 0.5-1.0 times,and the calcination temperature is 500-600?C.The results demonstrate that the catalytic activity and stability of SBMCs are very high.The initial acetylene conversion of SBM-1.0Zn-600 is as high as 99%under the reaction conditions at 200?C and acetylene space velocity of 1.0 mL/?min?g?,after120 h of reaction,the conversion of acetylene can reach more than 96%,and no obvious inactivation is observed.We also evaluate the stability of SBM-0.5Zn-600and find that its conversion of acetylene remains at about 90%after 320 h of reaction.No obvious deactivation is observed,which shows a certain industrial application prospect.We have carried out a series of material characterization of the obtained SBMCs catalysts and find that although no nitrogen source is added,there exists higher nitrogen content in the SBMCs.Additionally,Since nitrogen is derived from the soybean meal raw material itself,the SBMCs has a larger doping amount and a more uniform distribution is a higher quality nitrogen-doped carbon material.In addition,we find that the nitrogen chemical states mainly present in SBMCs are pyrrolic-N and pyridinic-N.Previous studies have shown that these two nitrogens are the main active sites for acetylene hydrochlorination.