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本工作从理论和实验方面探讨应用脉冲色谱法研究催化剂表面可逆吸附中心的强度和数目的可能性,结果表明: (1)在相同或相似条件下,可以通过测定同种反应物在一系列催化剂上可逆吸附过程中热力学函数变化的相对大小,比较不同催化剂上可逆吸附中心的相对强度和相对数目。 (2)在一定条件下,可以根据克分子吸附热的相对大小,比较不同催化剂上可逆吸附中心的相对强度;根据克分子吸附熵变的相对大小或lgV_n-1/T_c图上截矩的相对大小,比较不同催化剂上可逆吸附中心的相对数目。 (3)氧化苯为顺酐的钒催化剂中添加磷后,可逆吸附中心的强度增强,与此同时,可逆吸附中心的数目减少;氧化邻二甲苯为苯酐的钒磷钾催化剂经过长时间催化反应后,伴随着可逆吸附中心的强度增强,可逆吸附中心的数目减少。
This work explored the possibility of using pulsed gas chromatography to study the intensity and number of reversible adsorption centers on the catalyst surface from both theoretical and experimental aspects. The results show that: (1) Under the same or similar conditions, The relative sizes of the thermodynamic functions in the reversible adsorption process were compared, and the relative intensities and relative numbers of reversible adsorption sites on different catalysts were compared. (2) Under certain conditions, the relative intensities of reversible adsorption centers on different catalysts can be compared according to the relative molecular heats of adsorption; according to the relative size of the molecular adsorption entropy or the relative intercept of the lgV_n-1 / T_c diagram Size, compare the relative number of reversible adsorption centers on different catalysts. (3) The phosphorus in the vanadium catalyst with maleic anhydride as oxidation catalyst increased the intensity of the reversible adsorption center, meanwhile, the number of reversible adsorption centers decreased; the vanadium-phosphorus-potassium catalyst with o-xylene as phthalic anhydride had a long time catalytic reaction After that, with the increase of the intensity of the reversible adsorption center, the number of reversible adsorption centers decreased.