Papers by Keyword: Pd/C Catalyst

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Authors: Cheng Zhang, Pei Pei Sun, Wu Di Zhang, Yu Bao Chen, Fang Yin, Ling Xu, Xing Ling Zhao, Jing Liu, Shi Qing Liu
Abstract: The catalytic deoxygenation experiments of stearic acid and hydrogen were performed for 6 hours in the presence of a solvent, dodecane, in a temperature range of 295-305°C and the rotational speed of 100rpm, under a certain hydrogen partial pressure (in argon), using palladium supported on active and mesoporous carbon as a catalyst. The results showed, the main liquid-phase product was n-heptadecane, while the main gaseous products were CO2 and CO. When the partial pressure of hydrogen is 3.0MPa, the acid value of primary product is the lowest and the reaction tends to be gentle, conversion rate of stearic acid and selectivity to n-heptadecane is the highest.
Authors: Ya Long Liao, Xi Juan Chai, Fu Chang Xu
Abstract: Pd/C catalyst was used to eliminate chlorine compacted in shellac while it was being bleached with sodium hypochlorite in alkaline solution for the preparation of shellac with low chlorine content, a natural and biological product used in large scale in food industry and pharmaceutical fields. Experiments demonstrated that the Pd/C could catalyze dechlorination process effectively, which was affected by several factors such as reaction temperature, Pd/C ratio, and the induction of Pd/C catalyst, and that the dechlorination efficiency reached 88.2% under the optimal conditions of Pd/C loading ratio of 1.0% (mass), catalyst usage 12 g/L, H2 flowing rate 50 mL/min, and reaction temperature 90 for 120 min. Moreover, the mechanism of catalytic hydrogenation was elucidated through structure characterization of the final products using elementary analysis, and ultraviolet spectrophotometer. It was shown from the result of ultraviolet spectrophotometer that the wavelength of the maximum absorption of seedlac, the raw materials for obtaining shellac, was 235 nm. However, it was blue shifted to the same scope 220~225 nm when the shellac was dechlorinated by catalytic hydrogenation with Pd/C as the shellac without catalyzed. The big difference of wavelength of the maximum absorption between shellac and seedlac was due to that there was a lot of compacted chlorine in the shellac, while the little difference of wavelength of the maximum absorption between the shellac and the low chlorine shellac was due to that chlorine could not be eliminated completely. The results of elementary analysis showed that chlorine content in the final product was only 0.30% under the optimum conditions, compared to shellac it was just 1/9 of that of the product without declorination by catalytic hydrogenation. It was shown from the mechanism analysis that the dechlorination reaction took place mainly on the active surface sites of Pd/C, and chlorine ions compacted in the shellac was substituted by hydrogen ions.
Authors: Liang Wu Bi, Qiu Ge Zhang, Peng Wang, Zhen Dong Zhao, Da Wei Li, Yu Xiang Chen, Dong Mei Li, Yan Gu, Jing Wang, Xian Zhang Liu
Abstract: Turpentine-based dipentene (TBDP) contains limonene 30.32 %, terpinolene 31.35 %, α-terpinene 7.55 %, γ-terpinene 6.40 % and p-cymene 12.87 %. Three Pd/C catalysts were characterized by BET, XRD, TG-DTG and atomic absorption spectrometry (AAS). The properties of the catalysts on TBDP conversion were compared. Difference of catalytic competitive reactions of TBDP by catalyst A with the change of reaction temperature was discussed in detail. The yield of p-cymene at 280-310°C was over 95.0 %. It was important to control the reaction temperature for TBDP dehydrogenation catalyzed by Pd/C catalysts. It is valuable to probe the catalytic behaviors of Pd/C catalyst on TBDP dehydrogenation for research and development of efficient preparation technology of p-cymene from TBDP.
Authors: Xue Feng Bai, Hai Yang Wang
Abstract: The Pd/C catalyst with high dispersion was prepared by the activated carbon loading palladium nanoparticles (Pd-NPs) obtained in the protection of Tween-60. The above-prepared Pd/C catalyst was characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), chemical adsorption instrument. The influences of the size, dispersion, crystal type and electronic state of the Pd/C catalyst on catalytic activity were investigated. The results of Suzuki coupling reaction over the above-prepared Pd/C demonstrated that the reaction yield of aryl bromide under the conditions of 60°C for 1 h and para-chloronitrobenzene under the conditions of 80°C for 12 h reach 99% and 73% respectively.
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