0.5 wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants
0.5 wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants
复制标题
DOI：
10.1016/j.jcat.2011.03.012
复制
发表时间：
2011-06-13
影响因子：
7.3
通讯作者：
Lamberti, C.
中科院分区：
文献类型：
--
作者：
Pellegrini, R.;Agostini, G.;Lamberti, C.
对从装有相同新鲜催化剂（0.5 wt.% Pd/C，D3065 型，由 Chimet SpA 提供）的不同对苯二甲酸纯化反应器中取出的几种废催化剂进行了系统研究。通过 TEM 结合 EDS 检测对具有不同寿命、在催化床中的位置、烧结程度和污染物类型（主要是 5、Pb 和 Mo）的废催化剂进行了研究。 XRPD、EXAFS 光谱和 CO 化学吸附。 Pd烧结过程涉及所有催化剂，无论污染物的性质和数量如何，除了S中毒外，对烧结速率没有影响。 Pd 烧结按照不同的步骤发生，导致形成较大的晶体、聚集体和附聚物，最后是 Pd 表面积损失并因此导致催化活性下降的主要原因。在所研究的污染物中，S 和 Pb 是最严重的，因为它们与 Pd 发生强烈相互作用，从表面吸附层（XRPD 无法检测到，但通过 EDS 图可见）到块状 Pd4S 或 Pd3Pb 合金（XRPD 很容易检测到）形成。在这两种情况下，催化活性都会降低。相比之下，Mo、Cr、Fe、Ti 和 Al 不会优先与 Pd 相互作用（尽管污染物以相关浓度存在，但未检测到合金）：已发现它们分布在整个催化剂表面上。因此，没有证据表明这些污染物对催化活性损失有直接影响。 (C) 2011 Elsevier Inc. 保留所有权利。
A systematic study on several spent catalysts, withdrawn from different terephthalic acid purification reactors loaded with the same fresh catalyst (0.5 wt.% Pd/C, type D3065, supplied by Chimet SpA), has been carried out. Spent catalysts characterized by different lifetimes, position in the catalytic bed, sintering degree, and types of contaminant (mainly 5, Pb, and Mo) have been investigated by TEM coupled with EDS detection. XRPD, EXAFS spectroscopy, and CO chemisorption. The Pd sintering process involves all catalysts, irrespective of the nature and amount of contaminants that have no influence on sintering rate except for S poisoning. Pd sintering occurs following different steps, leading to the formation of larger crystals, aggregates, and agglomerates, the last being the primary cause of the loss of Pd surface area and, consequently, of the decrease in catalytic activity. Among the investigated contaminants, S and Pb are the worst, because they strongly interact with Pd, forming from surface adlayers (not detectable by XRPD, but visible by EDS mapping) up to bulk Pd4S or Pd3Pb alloys (easily detectable by XRPD). In both cases, the catalytic activity decreases. In contrast, Mo, Cr, Fe, Ti, and Al do not interact preferentially with Pd (no alloys have been detected, although the contaminants are present in relevant concentrations): They have been found to be spread on the whole catalyst surface. Accordingly, no direct effect of these contaminants on catalytic activity loss has been evidenced. (C) 2011 Elsevier Inc. All rights reserved.