3-氯甲苯在磷酸镧催化剂上常压水解动力学方程和机理的研究

KINETICS EQUATION AND MECHANISM OF HYDROLYSIS OF 3-CHLOROTOLUENE OVER LANTHANUM PHOSPHATE UNDER ATMOSPHERE

在633～673K,用氢作载气,通过曲线拟合测得了3-氯甲苯在LaPO_4-Cu和LaPO_4催化剂上常压水解的初始反应速率,得到了经验速率方程和动力学方程,并求出了有关参数。发现微量铜助剂对3-氯甲苯的吸附系数b_A影响不大,却使表面反应速率常数比原来LaPO_4提高约26倍;产物HCl的吸附系数b_c特别大,比b_A大11倍,因此对水解反应速率有很大的阻抑作用。结合催化剂表面酸性的程序升温脱附考察结果,推断水吸附在L酸中心,3-氯甲苯主要吸附在B酸中心,表面反应为速率控制步骤。在LaPO_4-Cu上,3-氯甲苯的吸附热为68.2KJ/mol,表面反应的活化能为213.6KJ/mol。数据处理和参数确定均用最小二乘回归法。

The initial reaction rate of hydrolysis of 3-chloro-toluene over LaPO_4-Cu andLaPO_4 catalysts at 633～673K in hydrogen carrier gas was measured by curve mode-ling.The empiric rate equation and kinetics equation with parameters were deter-mined.It is observed that promoter copper has almost no effect on the adsorptioncoefficient b_A of 3-chloro-toluene,but increases the surface reaction rate constent26 times than LaPO_4 catalyst.The adsorption coefficient b_c of product HCl islarger 11 times than b_A,so to be strong inhibiting action on hydrolysis.Combiningwith investigating the acid properties of the catalysts by temperature program de-sorption,it is proposed that water is adsorbed on L acid center,3-chloro-toluenemainly adsorbed on B acid center,the surface reaction of them is rate determiningstep.The adsorption heat of 3-chloro-toluene on LaPO_4-Cu is 68.2kJ/mol.The acti-vation energy of surface reaction is 213.6KJ/mol.Mean square regress was used indata processing and evaluation of parameters.