Study On Hydrogen Donor For Conversion Of Carbon Tetrachloride To Chloroform Through Hydrodechlorination

Carbon tetrachloride(CTC)is a by-product of the methane chlorides(CMs)production.China is the largest producer of CMs in the world with 2.46 million tons CMs output and 123,000 tons of CTC by-products in 2017.CTC as an ozone depleting substance(ODS)is a controlled chemical,and it is only allowed to be used as a raw material for the production of non-ODS.In order to fulfill the Montreal Convention and eliminate CTC production and consumption,CMs manufacturers must build the onsite conversion devices to incinerate or convert their CTC to non-ODS substances.Therefore,development of carbon tetrachloride conversion technology is of great practical value.Chloroform is a bulk chemical and an important CMs product.Converting CTC to chloroform can not only solve the ODS disposal problems,but also achieve resource utilization of CTC with high atomic using efficiency and obvious economic benefits.This paper proposed a novel method for the conversion of CTC to chloroform via hydrodechlorination.Three hydrogen donors(trichloroethylene,succinimide,and tetrahydronaphthalene)were studied for the hydrodechlorination of carbon tetrachloride.The effects of hydrogen donor,temperature,type and amount of catalyst on CTC conversion,kinetics and scaleup effect were studied.The products are analyzed quantitatively and qualitatively by gas chromatography and gas chromatography-mass spectrometry.The results show that when trichloroethylene is used as the hydrogen donor,the reaction can be completed within 0.5 h with 95%of Chloroform selectivity at the following conditions,i.e.30-60?,9 g CTC,10 mmol trichloroethylene,1 mmol TBAF,and 10 mmol K2CO3.When succinimide is used as hydrogen donor,91%of chloroform yield can be achieved when the reaction performed 4 h in a hydrothermal reactor at 150 ? and mole ratio of nNHs:nTBAF:nK2CO3=1:0.3:1.When tetrahydronaphthalene is used as a hydrogen donor,and reacted with CTC at 230? and nCTC:ntetrahydronaphthalene=1:1,over 90%of carbon tetrachloride conversion and 75%of chloroform selectivity can be achieved.The hydrogen donors proposed here can be used for the efficient conversion of CTC to chloroform under mild conditions,which is much superior to the traditional hydrodechlorination process that uses hydrogen gas and precious metal catalysts.The present method is simple to use,and suitable for industrial application.The present study is of great significance for the resource utilization of by-product CTC in the methane chloride production industry in China.