炭载硫化钯催化剂的水相合成及其催化性能研究

Aqueous Phase Synthesis of Activated Carbon Supported Palladium Sulfides and Their Catalytic Performance

研究了硫化温度、时间、气氛和原料投入比等对水相条件下Pd/C与Na2S反应的影响规律,合成出一系列具有不同硫化钯晶相的炭载硫化钯催化剂;以N-苯基对苯二胺的N-还原烷基化合成N-（1,3-二甲基丁基）-N＆#39;-苯基对苯二胺（6PPD）为探针反应考察了该系列炭载硫化钯的催化性能.研究发现,硫化温度和气氛是影响所合成的炭载硫化钯晶相结构的重要因素：随着硫化温度的升高（30～250℃）,在H2氛围下,只能形成Pd4S晶相;而在N2氛围下,却可合成出较高硫钯原子比的硫化钯晶相,如Pd4S-Pd3S和Pd4S-Pd3S-Pd16S7-PdS等.不同晶相的炭载硫化钯表面Pd原子的缺电子程度不同,从而表现出不同的催化性能.其中,在120℃、H2氛围下合成的Pd-Pd4S/C催化剂表现出最好的催化选择性（≥96.4％）和稳定性.

In this work, activated carbon supported palladium sulfides with different crystalline phases were synthesized by the aqueous phase reaction of Pd/C and Na2S . Their catalytic performance was investigated through the reductive N-alkylation of aromatic amines for the synthesis of N-（1, 3-dimethylbutyl）-N＇- phenyl-p-phenylenedianine （6PPD）. The experimental results suggest that the formation of special crystalline phase of palladium sulfides is highly dependent on the sulfidation temperature and surrounding gas. In H2, only Pd4S can be formed in a temperature ranging from 30 to 250℃. Higher S/Pd atomic ratio palladium sulfides, such as Pd4S-Pd3S and PdaS-Pd3S-Pdl6S7-PdS, can be obtained in N2. Furthermore, different phases show different electron-deficient degrees of surface Pd, therefore, they exhibited diverse catalytic activity and stability for the synthesis of 6PPD. Pd-Pd4S/C catalyst formed in H2 at 120℃ shows the best catalytic selectivity （≥ 96.4%） and stability.