吸附强化异构反应过程分析

Analysis of a sorption-enhanced isomerization reaction process (SEIRP)

提出以吸附强化可逆异构反应的变压循环过程,构建了平衡条件下的模型,考虑了线性和扩展Langmuir两种类型的吸附等温线。根据模型计算反应所能达到的转化率,结果表明脱附物料中反应物的转化率显著高于反应平衡转化率。考察了脱附物料转化率的变化规律,当采用线性吸附等温线时,只有选择性系数、吸附压力和脱附压力的取值对转化率有影响:脱附物料转化率随选择性系数增大而增大,极限值为1;脱附物料转化率随吸附压力增大而增大,极限值为α_(B/A)K_p/(1+α_(B/A)K_p)。当采用扩展Langmuir等温线时,饱和吸附量Qm的取值不影响脱附物料转化率,而Langmuir常数bB的取值对其有影响。此外还分析了气相与吸附相物料相对比例、脱附过程逆向反应对强化效果的影响。

A pressure swing process combined with a reversible isomerization reaction and adsorption is explored. An active catalyst for the reversible isomerization reaction A■■B and an adsorbent which preferentially adsorbs product B are mixed and loaded in one bed. At least two steps are needed,reaction and adsorption at high pressure,plus desorption at low pressure. Models which assume reaction equilibrium and adsorption equilibrium have been formulated,employing linear adsorption isotherms and extended Langmuir isotherms respectively. Values of Xde(the mole fraction of B in the desorbed material） under different conditions were calculated,and the values were found to be significantly higher than the reaction equilibrium conversion. The pressure and selectivity of the adsorbent between B and A were found to be the main factors determining Xde. When linear adsorption isotherms are assumed,Xdeincreases with increasing values of αB/Aor adsorption pressure,and the limits are 1 and α（B/A）Kp/(1 ＋ α（B/A）Kp）,respectively. When extended Langmuir isotherms are assumed,Qm(the saturated adsorption capacity） has no effect on Xde,and bB(the Langmuir isotherm constant）. The effect of varying the distribution between adsorbed phase and gas phase was calculated. The reverse reaction in the desorption step is also discussed.