烯烃在USY沸石表面上化学反应热的量热测定

1.前言 在多相催化研究工作中,测定反应物分子在固体催化剂表面上化学吸附时产生的反应热,或者说化学吸附热,对研究催化剂的性质和反应物的表面化学反应都很有帮助。但是目前尚无有效的方法测定它。本文用吸附量热法测定了烯烃在USY沸石表面的吸附热,并提出了一种化学吸附热的估算方法。

Calorimetric Measurement of Surface Reaction Heats of Alkenes on USY Zeolites

Differential heats of adsorption (DHA) of alkenes and alkanes having similar structures on USY zeolite were measured with a SET ARAM microcalorimeter. IR spectra of corresponding adsorptive systems were also given. The DHA(Q) of alkenes on strong Bronsted acid sites of USY zeolite were considered as the sum of two parts: the surface reaction heats(Qc) of C=C-+ HO-Z=H-C-C-O-Z , and the DHA of physical adsorption (Qp) of the adsorbed alkene molecules. i. e. Q=QC+QP. By replace- ing the Qp of the alkenes with the DHA of similar alkanes, Qc were calculated according to QC=Q-Qp. The Qc thus obtained agreed quite well with that calculated by the Benson group using the addition method. The surface reaction heats of alkenes on USY zeolite were shown in Table 1.