Catalysis Science & Technology
·
2021
·Vol. 11
·期 10
·3609-3618
·
IF 6.119
Palle Ramana Murthy,Jing-Cai Zhang,Wei-Zhen Li
Pd-Based catalysts are efficient for methane combustion but impractical at high temperatures due to the sintering effect. Herein, we report a thermally stable Pd/SBA-15 catalyst that was prepared by using the sol-immobilization (SI) method, instead of the conventional incipient wetness impregnation (IWI) method. Pd nanoparticles retain the small size of ∼5 nm in the channels of SBA-15 in Pd/SBA-15-SI even after aging at 800 °C in air for 3 days, while those in the Pd/SBA-15-IWI samples aggregate into particles larger than 10 nm over the surface. The thermally stable Pd/SBA-15-SI indeed displays excellent catalytic activity for methane combustion at low temperatures with T50 at ∼300 °C and T90 at ∼350 °C and high stability during cyclic operations, which are much superior to those of the Pd/SBA-15-IWI catalysts. Interestingly, hydrothermal treatment of the Pd/SBA-15-SI catalysts leads to partial re-dispersion of Pd to form smaller particles of ∼1.6 nm, while the catalytic activity decreases a bit. Steam in the reactant mixture has a negative effect on the catalytic activity of Pd/SBA-15-SI catalysts, presumably due to the competitive adsorption of H2O to O2/CH4. Significantly, the size of Pd nanoparticles is essential to the catalytic performance and those having sizes of ∼5 nm are the most active. Finally, the catalytic activity of the catalysts in the presence of CO2 was studied. This work might be helpful in designing stable metal catalysts using porous materials for reactions under harsh conditions.
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2016
·
IF 3.652
Qiang Lu,Zhi-bo Zhang,Xiao-ning Ye,Wen-tao Li,Bin Hu,Chang-qing Dong,Yong-ping Yang
A new technique was proposed to selectively produce 4-ethyl guaiacol (4-EG), a valuable phenolic compound, via low-temperature catalytic fast pyrolysis of softwood biomass using the Pd/SBA-15 catalyst. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to compare 4-EG production from three biomass materials with different lignin types (pine wood, poplar wood and bagasse) and two catalytic patterns (in-situ and ex-situ). Further experiments were performed to reveal 4-EG formation affected by the pyrolysis temperature, catalyst-to-biomass ratio and Pd content of the Pd/SBA-15 catalyst. The results indicated that 4-EG could be selectively produced from pine wood by the in-situ catalytic pattern. 4-EG was a very minor pyrolytic product in the non-catalytic process, while it could be selectively produced in the catalytic process, via the decomposition and hydrogenation of lignin. Our results suggested that several holocellulose-derived pyrolytic products could serve as the hydrogen-donors (H-donors) for the formation of 4-EG, without any extra H-donors. The highest 4-EG yield of 18.44 mg/g from pine wood was obtained at the temperature of 350 °C and catalyst-to-biomass ratio of 2, and the corresponding peak area% (calculated by GC/MS) was 38.34%.
研究领域:
能源与燃料化学
·
生物质转化技术
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 59
·34581-34588
·
IF 3.049
Li Wang,Yue Zhang,Qingqing Ma,Zhiyong Pan,Baoning Zong
Organosilane-functionalized mesoporous silica SBA-15 was prepared by the co-condensation method and then applied as a support of Pd catalysts for hydrogenation of 2-alkyl-anthraquinone (AQ, alkyl = ethyl, tert-butyl and amyl). The as-prepared Pd catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, N2 adsorption–desorption, zeta potential, water contact angles measurement and transmission electron microscopy. By extending the pre-hydrolysis time of the silica source, the content of functional groups in the catalysts slightly increases. However, there is an initial increase in zeta potential and water contact angles up to a maximum at 2 h, followed by a decrease as the pre-hydrolysis time was further prolonged. The hydrophobicity created by organic functionalization has positive effects on AQ hydrogenation. The catalyst with the highest hydrophobicity exhibits the highest catalytic activity, with increments of 33.3%, 60.0% and 150.0% for hydrogenation of ethyl-, tert-butyl- and amyl-anthraquinone compared with the unfunctionalized one.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2015
·
IF 3.564
Zhi-bo Zhang,Qiang Lu,Xiao-ning Ye,Wen-tao Li,Ying Zhang,Chang-qing Dong
A new technique was proposed to selectively produce 4-ethyl phenol (4-EP) from low-temperature catalytic fast pyrolysis of certain herbaceous biomass, while 4-vinyl phenol (4-VP) could be selectively produced from non-catalytic fast pyrolysis process. In this study, Pd/SBA-15 catalysts were prepared, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique was applied for both ex situ and in situ catalytic fast pyrolysis of bagasse . The results indicated the 4-EP could be selectively produced from both catalytic methods. During the ex situ catalytic pyrolysis process, the bagasse would decompose to form 4-VP which was then hydrogenated by the Pd/SBA-15 catalyst to be 4-EP. During the in situ catalytic pyrolysis process, the Pd/SBA-15 catalyst would catalyze the decomposition and hydrogenation of bagasse to directly produce 4-EP. Certain pyrolytic products would serve as the hydrogen-donors (H-donor) for the formation of 4-EP. The selectivity of the 4-EP from the ex situ catalytic process was a little better than that form the in situ catalytic process. The highest 4-EP yield from ex situ catalytic pyrolysis of bagasse was around 2.0 wt%, obtained at the pyrolysis temperature of 350 °C and catalyst-to-biomass ratio of 1.5.
研究领域:
能源与环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
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