Negative effect of Ni on PtHY in n-pentane isomerization evidenced by IR and ESR studies

查看全文 作　　者：Muhammad Arif Ab [1]Aziz;Nur Hidayatul Nazirah [1]Kamarudin;Herma Dina [1]Setiabudi;Halimaton [2]Hamdan;Aishah Abdul [1]Jalil;Sugeng [3]Triwahyono 机构地区：[1]Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia;[2]Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia;[3]Ibnu Sina Institute for Fundamental Science Studies, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia 出　　处：《Journal of Natural Gas Chemistry》索引2012年第21卷第1期,共8页 基　　金：supported by the Ministry of Higher Education, Malaysia through Fundamental Research (Grant Scheme No. 78670);the UTM Short Term Research (Grant No. 77330) 摘　　要：Ni/PtHY with different Ni loadings was prepared by impregnating HY with hexachloroplatinic acid solution and Ni2+/N,N-dimethylformamide solution. An increase in the Ni loading decreased the crystallinity, specific surface area and meso-micropores of the catalysts. Ni interacted with hydroxyl groups to produce IR absorption bands at 3740-3500 cm-1. Increasing Ni loadings resulted in a decrease in the intensities of the broad bands at 3730-3500 cm-1 and the sharp band at 3740 cm-1 with simultaneous development of new absorbance band at 3700 cm-1 that was attributed to (-OH)Ni. The acidity of the samples did not significantly change with Ni loadings up to 1.0 wt%, which indicated that Ni mostly interacts with non-acidic silanol groups (terminal- and structural-defect OH groups). The presence of Ni decreased the activity of PtHY toward the isomerization of n-pentane because of a decrease in the number of active protonic-acid sites that formed from molecular hydrogen. IR and ESR studies confirmed that Pt facilitated the formation of protonic-acid sites from molecular hydrogen, whereas Ni, even when combined with Pt, didn't exhibit such ability. The absence of protonic-acid sites from molecular hydrogen significantly decreased the yield of iso-pentane and markedly increased the cracking products. 关 键 词：异构化 正戊烷 ESR IR N-二甲基甲酰胺 镍 证明 溶液浸渍