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采用连续流动的固定床微反装置考察了Pt/SO24-/ZrO2-Al2O3(PSZA)在正己烷异构化反应中的催化行为。采用NH3-TPD、H2-TPR及TG表征了催化剂的酸性、还原性能及硫物种含量。结果表明,PSZA的初始异构化催化活性几乎不受反应温度的影响,而稳定性则与反应温度密切相关。低温下反应,催化剂在短时间内迅速失活,而提高反应温度可大大提高PSZA的反应稳定性。PSZA具有良好的再生性能,与新鲜催化剂相比,多次再生后的催化剂异构化催化活性基本没有变化。PSZA在低温下的快速失活与其催化活性中心产生的机理有关,而与其硫损失或硫物种的还原无关。在异构化反应过程中,催化剂通过氢溢流可产生强酸活性中心,并在反应过程中不断被消耗;在高温下通过氢溢流不断产生新的强酸中心,使催化活性保持稳定;而低温下氢溢流难以发生,消耗的强酸活性中心不能及时补充,使催化活性下降。
The catalytic behavior of Pt / SO24- / ZrO2-Al2O3 (PSZA) in the isomerization of n-hexane was investigated using a continuous flow, fixed bed micro-reactor. NH3-TPD, H2-TPR and TG were used to characterize the catalyst’s acidity, reduction performance and sulfur species content. The results showed that the initial isomerization catalytic activity of PSZA was almost unaffected by the reaction temperature, while the stability was closely related to the reaction temperature. Reaction at low temperature, the catalyst rapidly inactivated in a short time, and improve the reaction temperature can greatly improve the PSZA reaction stability. PSZA has a good regeneration performance, compared with the fresh catalyst, after repeated regeneration of the catalyst isomerization catalytic activity basically no change. The rapid deactivation of PSZA at low temperatures is related to the mechanism by which its catalytically active center is generated, regardless of its sulfur loss or the reduction of sulfur species. During the isomerization reaction, the catalyst can generate strong acid active sites through the overflow of hydrogen and is consumed continuously during the reaction; new strong acid centers are continuously produced through overflow of hydrogen at high temperature to keep the catalytic activity stable; while the low temperature Lower hydrogen overflow difficult to occur, the consumption of strong acid active center can not be replenished, so that the catalytic activity decreased.