| Calcium carbide(CaC2)is an important coal chemical,and extending its application is of great significance for the sustainable development of coal chemical industry.However,the present calcium carbide sector suffers from singleness of the downstream consumption and high pollution of relative processes,as well as little utilization of its intrinsic chemical properties.Thus,it is necessary to explore its new chemical reactions for direct synthesis of high-value chemicals,so as to realize sustainable development of CaO2 industry.At present,CaC2 is mainly used as a solid source of C2H2 to improve the process safety,being an extension of acetylene chemistry.Thus,trace amount of water is required to hydrolyze CaC2 slowly,and most of the studies are only on a laboratory scale and far from practical application.In this thesis,we studied the mechanical activation of CaC2 and its mechanochemical reactions with chlorinated polymers to synthesize carbon materials,its base catalysis for the condensation of ketones,and mechanochemical reaction with alcohols for the synthesis of calcium alcoholates and C2H2.Besides,their reaction mechanisms,the influencing factors of the reactions,as well as the potential applications of the resultant products were studied.Firstly,carbon materials were prepared via mechano-and thermo-chemical reactions of CaC2 with chlorinated polymers,respectively,and their differences in product structure and reaction mechanism were studied.The results show that the mechanochemical reaction proceeds as a nucleophilic substitution of Cl in the polymers by C=C groups in CaC2,resulting in 3D carbon materials(CMs-M)with high crosslinkage.In contrast,the thermochemical process starts from thermal decomposition of chlorinated polymers along with violent reaction with CaC2,forming mixed carbon materials(CMs-T)with different structure.The mechanochemical method is more suitable for massive production of CMs in view of its complete reaction,mild operation condition and controllable process.In comparison with CMs-T,CMs-M possess higher specific area,richer pore structure and C?C,C-O and COOH groups,and lower graphitization degree.Secondly,the adsorptive and electrochemical performance of as-prepared CMs-M and CMs-T were investigated,respectively.In comparison with CMs-T,CMs-M possess higher specific area and rich functional groups,and accordingly higher adsorptivity for dibenzothiphene(DBT)and Hg2+.For the adsorption isotherm of DBT on CMs,Freundlich model is more suitable to describe it,indicating a multilayer physical process.For the adsorption isotherm and adsorption kinetics of Hg2+ on CMs,Langmuir model and pseudo-second-order model is suitable,respectively,suggesting a monolayer chemosorption.CMs-M exhibit excellent Hg2+ adsorption capacity with saturated adsorbance of 291.2 mg·g-1,which manifests the chemisorption arising from the unique interaction between Hg2+ and the functional groups of acetylenic and O-containing groups,thus may be deemed as one of the best carbonaceous sorbents for Hg2+.Besides,it shows excellent recyclability,indicating a great potential for industrial application.On the other hand,all CMs exhibit representative capacitive behavior and good charge-discharge reversibility as electrode materials in supercapacitor,and CMs-T is better for its stability under different scan rates and current densities.In addition,CMs exhibit high electrical conductivity and rapid charge and discharge performance,as well as excellent cycling stability with their capacitance maintenance above 92%after 1000 cycles of charge and discharge,suggesting their good usability as electrode materials.On the whole,CMs-T possess high graphitization degree and ordered structure,and accordingly slightly better electrochemical performance than that of CMs-M.Therefore,CMs-M are more suitable to be used as adsorption or catalytic materials considering their large specific surface area and abundant functional groups,while CMs-T are more beneficial to be used in high-performance capacitors with their high degree of graphitization.Thirdly,CaC2 were used as catalyst and packing in a catalytic distillation(CD)process for the aldol condensation of acetone.With this process,diacetone alcohol(DAA),mesityl oxide(MO)and isophorone(IP)are synthesized efficiently along with high total selectivity of(DAA,MO and IP)and conversion of acetone,simultaneously.Lower temperature and higher reflux rate favor the production of DAA and MO.The catalytic distillation process realized an excellent control of reaction temperature,instant separation of products and effective control of product composition,resulting in a higher conversion of acetone and selectivity of DAA,MO and IP simultaneously.Meanwhile,the strong basicity of CaC2 is fully utilized before its hydrolysis to acetylene.The catalysis of CaC2 for the condensation of acetophenone was also studied,which coupled the aldol condensation of acetophenone and hydrolysis of CaC2.Higher temperature is beneficial to the condensation of acetophenone,but with too long reaction time,excessive condensation products are formed.Increasing the CaC2 amount and reducing its particle size are conducive to the condensation reaction.Finally,we studied the mechanochemical reaction of CaC2 with methanol,ethanol and glycol to produce calcium alcoholates and C2H2.The reaction process is mild,controllable,and efficient.The empirical correlation was established for the conversion rate of CaC2.The conversion rate of CaC2 is negatively correlated with the number of carbon atoms of alcohols and positively correlated with the number of OH and rotational speed.The influence of the number of carbon atoms and OH groups in alcohols is more significant.The reaction kinetics of CaC2 with methanol,ethanol and glycol can be satisfactorily correlated by the Avrami-Erofeyev model. |
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