Preliminary Study On Acetylene Hydrochlorination

Vermiculite has various properties, such as low cost, good adsorption and ion exchange properties andgood wear resistance, which is widely applied to the adsorbent, catalyst carrier, etc. First, the experimentfocused on the expansion technology research of vermiculite and then Na2S and chitosan were used tomodify expanded vermiculite. The adsorption Hg2+behavior of the two adsorbents was investigated, theadsorption theory as the foundation, further prepared HgCl2/modified vermiculite catalyst, preliminaryexploration of HgCl2/modified vermiculite catalyst on catalytic properties of acetylene hydrochlorinationand the deactivation reason is analyzed.Vermiculite was characterized by XRF, XRD, SEM, IR. By comparing the expansion rate, the optimalsize of vermiculite was: thickness of0.6-1.5mm, particle size of7-8mm. Three methods were used toexpand the vermiculite (calcining, microwave, H2O2). The best expansion condition was: calcination time is80s, calcination temperature is1000℃; Microwave power for high fire, the time is60s; H2O2concentration was25%. The optimal expansion technology: H2O2and microwave modification expansiontechnology:25%H2O2, microwave is high fire, the time is60s, the expansion ratio is47.68times.This study researched the adsorption performance of Hg2+removal using the Na2S modifiedvermiculite from aqueous solution. The optimum adsorption conditions were as follows: the concentrationof Na2S was1.5mol/L, pH was6, adsorbent amount was0.2g, treatment time was30min. Adsorptionkinetic data showed that the adsorption could be better described by the pseudo-second-order kinetic modelthan the pseudo-first-order model. Adsorption equilibrium was better described by the Freundlich isothermthan the Langmuir isotherm. The calculated thermodynamic parameters (G, H, and S) showed that theremoval of Hg2+by Na2S modified vermiculite was spontaneous, exothermic.This study focused on the adsorption behavior of Hg2+removal using the chitosan modifiedvermiculite. The optimum adsorption conditions were as follows: pH6, chitosan amount of0.05g/g,treatment time of40min. Adsorption kinetic data were analyzed by the pseudo-first-order andpseudo-second-order models. The results showed that the process could be better described by thepseudo-second-order kinetic model. Adsorption equilibrium was better described by the Freundlichisotherm than the Langmuir isotherm. The calculated thermodynamic parameters (G, H, and S) showedthat the removal of Hg2+by chitosan modified vermiculite was spontaneous, exothermic, and feasible.Preparation of HgCl2/expanded vermiculite, HgCl2/chitosan expanded vermiculite and HgCl2/chitosanexpanded vermiculite+fertilizer catalyst, and applied to the acetylene hydrochlorination.The experimentalresults showed: the catalyst modified by chitosan has higher catalytic performance and life, and furthermodified by fertilizer, the conversion was improved, which was more than99%, but the conversion ratewas not high.Using thermogravimetric analysis and appearance observation, found tnat HgCl2loss andcarbon deposition were the main reasons for catalyst deactivation.