摘要
为了研究Pd/SiO_2杂化材料的热力学性能,以正硅酸乙酯、甲基三乙氧基硅烷为前驱体,氯化钯为钯源,采用溶胶-凝胶法制备Pd/SiO_2杂化材料。采用TG-DTG技术对其进行热分析,利用KAS和FWO法计算热分解活化能Ea,根据主曲线法确定热分解的机理函数,并计算峰温下不同升温速率时的平均活化焓ΔH≠、活化熵ΔS≠、活化Gibbs自由能ΔG≠。结果表明,Pd/SiO_2杂化材料的热分解过程分为3个阶段。第1阶段为水分子和醇的挥发,第2阶段为未完全水解反应物的分解和Pd^(2+)的还原/氧化,第3阶段为甲基的分解和部分Pd0的氧化。3个阶段的ΔG≠、ΔH≠值均随着温度的升高而增加,其值都大于0。Pd的负载增大了甲基热分解反应阶段的活化能。
In order to study the thermodynamic properties of Pd/SiO2 hybrid materials, using tetraethoxysilane and methyl triethoxysilane as precursor, PdCl2 as palladium source, the Pd/SiO2 hybrid materials were prepared by sol- gel method. The thermal decomposition process was investigated by applying the TG-DTG technique. The decomposition activation energies were calculated by KAS and FWO methods. The decomposition mechanism functions were determined according to the main curve method. The average activation enthalpy AH# , activation entropy ASS and apparent activation Gibbs free energy AG# under characteristic temperature Too were also figured out. The results show that the thermal decomposition of Pd/SiO2 hybrid material can be divided into three stages. The first stage is the volatilization of water molecules and alcohols, the second stage is the decomposition of incomplete hydrolysis reactants and the reduction/oxidation of Pd2 ＋ , and the third stage is the decomposition of the methyl groups and the oxidation of some Pd0. The values of ΔG≠ and ΔH≠ in the three stages increase with the increasing temperatures which are all greater than zero. The doping of palladium increases the activation energy of -CH3 group decomposition stage.
出处
《化学工程》
CAS
CSCD
北大核心
2016年第12期36-40,共5页
Chemical Engineering(China)
基金
国家自然科学基金资助项目(21573171)
陕西省自然科学基金资助项目(2016JM5042)
陕西省教育厅自然科学专项基金(16JK1325)
西安工程大学创新基金(CX2014028)
关键词
Pd/SiO2杂化材料
热分解
热分析动力学
热力学
Pd/SiO2 hybrid materials
thermal decomposition
thermal analysis kinetics
thermodynamics
作者简介
杨靖（1976-），女，教授，主要从事膜分离技术的研究，电话：13572290691，E-mail：jingy76@163．com。
