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The support of MgO/γ-Al2O3 was initially prepared by a multiple impregnation method and Pd was placed on the surface of the MgO/γ-Al2O3 support via incipient wetness impregnation. Pd/MgO/γ-Al2O3 (Pd/MAO) catalysts were systematically characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), CO2-temperature-programmed desorption (TPD), transmission electron microscopy (TEM), CO-Fourier transform infrared (CO-FTIR), and X-ray photoelectron spectroscopy (XPS) and tested in the CO oxidative coupling to dimethyl oxalate (DMO) reaction. Compared to Pd/γ-Al2O3, the catalytic activities of the Pd/MAO catalysts improved significantly. The Pd/MAO catalyst with a 30% mass ratio of Mg to γ-Al2O3 delivers 3 times higher STY of DMO than that of Pd/γ-Al2O3. It has been demonstrated that MgO covered γ-Al2O3 layer-by-layer forming MAO supports, which can increase surface basicity and the interaction between Pd particles and the MAO supports. Moreover, the relationship between metal and support interaction and catalytic performance was discussed.

Highly active MoS2 catalysts were developed by tuning the precursors and synthesis solvents to upgrade unconventional feedstocks into light fuels through the slurry-phase hydrogenation reaction. A ...

Developing highly dispersed few stacking layer MoS2 nanocatalysts with high exposure of active sites is still a challenge in improving their catalytic activities. Herein, we report a facile strateg...

Sn-zeolites are important solid Lewis acid catalysts with wide applications to the conversions of various biomass-derived carbohydrates. As the catalytic center, framework Sn of Sn-zeolites can catalyze glucose isomerization to fructose and epimerization to mannose. In practical use, the main obstacle to the application of Sn-zeolites is the lengthy crystallization. In present work, we developed a rapid synthesis route to Sn-zeolites by incorporating Sn into the germanosilicate framework of BEC zeolite via direct hydrothermal procedure. The synthesis time required by Sn-BEC is tenfold shortened than that by the traditional Sn-zeolites like Sn-Beta. The locations of framework Sn atoms of Sn-BEC were investigated by 19 F MAS NMR and computational modeling, which indicates that the framework Sn sites of Sn-BEC adopt a uniquely homogenous distribution at the T 1 sites. Sn-BEC exhibits high reaction activity and single isomerization selectivity in the glucose conversion in methanol, while Sn-Beta shows both isomerization and epimerization selectivity. The single isomerization selectivity of Sn-BEC suggests the presence of single catalytic center, which is probably caused by the homogenous distribution of framework Sn sites.

Zeolite Beta containing ultra-small CoO particles was synthesized from a one-step hydrothermal process. The synthesis route involves the pre-mixture of hydrofluoric acid with tetraethylammonium hydroxide (in a molar ratio of 1.3–1.5:1) before the addition of a silicon and cobalt source. Investigations by scanning electron microscopy, X-ray diffraction, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, H 2 -temperature-programmed reduction and transmission electron microscopy confirm the presence of ultra-small CoO particles in the zeolite Beta structure. The ultra-small CoO particles in zeolite Beta present high stability against both oxidation and reduction atmospheres at high temperatures. The catalytic performance of the CoO-containing zeolite Beta catalysts was compared with other Co-containing zeolites by evaluating ethylbenzene oxidation reactivity. The CoO-containing zeolite Beta exhibits high ethylbenzene conversion and high selectivity to acetophenone and 1-phenylethanol. The high activity of this catalyst system can be attributed to the high dispersion of the ultra-small CoO particles in the Beta structure.

Pt/WOx–ZrO2 and Pt/ZSM-22 were prepared and used as catalysts for the n-pentane hydroisomerization reactions. The physico-chemical properties of the supports were characterized by XRD, N2 adsorption, NH3-TPD and 1-pentene isomerization reaction. The reducibility and adsorbability of the catalysts were evaluated via H2-TPR, H2-TPD and CO adsorption. Under the reaction condition of WHSV = 1 h−1, pn-pentane,0 = 0.24 bar and ambient pressure, the yields of isopentane over Pt/WOx−ZrO2 and Pt/ZSM-22 can reach 52% (at 300 °C) and 61% (at 340 °C) respectively. The selectivities to isopentane over these two catalysts are well above 95%. The hydroisomerization mechanisms over these catalysts are discussed.

The pore architecture and acidity of zeolite materials play crucial roles in the activity and selectivity of catalytic reactions. Herein, hierarchical SAPO-11 molecular sieve microspheres with uniform intercrystalline mesoporosity (ca. 4.3 nm) and tunable acidity were synthesized via dry-gel conversion (DGC) of a silicoaluminophosphate–organosilane composite. The products were comprehensively characterized using multiple techniques, including XRD, SEM, TEM, N2 adsorption–desorption, NH3-TPD, pyridine-adsorbed IR (Py-IR), TG and 29Si MAS NMR measurements. It is revealed that the products' acidity can be precisely tuned in a wide range by simply adjusting the water content used in the synthesis. The growth of such hierarchical SAPO-11 underwent a rearrangement of the mesopores: the original mesopores (ca. 17 nm) of the precursor were collapsed at the initial stage of crystallization and the final mesopores of the products were directed by the organosilane. More importantly, the Pt/hierarchical SAPO-11 catalysts exhibited enhanced isomerization selectivity in the hydroisomerization of n-dodecane, attributed to their excellent diffusion properties resulting from the hierarchical pore network. This work demonstrates a facile approach to synthesize hierarchical zeolites with tunable acidity, which is beneficial for catalytic reactions involving bulky molecules.

Metal-free carbocatalysts enriched with specific oxygenated groups with different morphology and size were synthesized from glucose by hydrothermal carbonization, in which cheap and widely available biomass could be converted into functionalized carbon using an environmentally benign process. The hydroxy- and carbonyl-enriched hydrothermal carbon (HTC) could be used in nitrobenzene reduction, and higher conversion was obtained on the sphere morphology with smaller size. In the Beckmann rearrangement of cyclohexanone oxime, carboxyl-enriched HTC exhibited superior performance compared with conventional solid acid (such as HY and HZSM-5), on which the strong acid sites and weak Lewis acid sites lead to high selectivity for the side product. Although the intrinsic acidity of carbon is weak, the carboxyl-enriched carbon was used in weak Brønsted acid-catalyzed reactions, such as the Beckmann rearrangement.

N‐doped graphene‐like layered carbon (NG) could be synthesized via a metal‐free pyrolysis route from glucose, fructose and 5‐hydroxymethylfurfural (5‐HMF), which are cheap and widely available biomass or biomass derivatives. Among the three kinds of NG, well‐developed thin layered structure with large lateral dimension could be obtained when 5‐HMF was used as the precursor. More importantly, the 5‐HMF derived NG could exhibit superior performance in epoxidation reactions compared with the conventional carbon catalysts and the performance of 5‐HMF derived NG was even similar to that of a Co catalyst. Co catalyst is widely studied in alkene epoxidation reactions. Characterizations by TEM and XPS accompanied by EPR analysis revealed that the origin of the enhanced catalytic properties for NG was ascribed to the activation ability both for alkene and O2, which was attributed to the graphitic layered structure and graphitic N species, respectively.

ZSM-22, ZSM-35 and ZSM-5, aluminosilicate zeolites possessing 10-membered ring channels, have been used in the present study as the catalysts of the MTO reaction. The diversities in dimensions and connection types of the 10-membered ring channels of the three zeolite catalysts make their performances in the MTO reaction quite different. As the key active species involved in the hydrocarbon-pool mechanism in the MTO reaction, methylcyclopentenyl cations (MCP+) and methylbenzenes have been captured by 13C MAS NMR and GC-MS over the three zeolite catalysts during methanol conversion. The comparative studies of the retained organics generation over the zeolite catalysts indicate that due to the spatial confinement effects of the inorganic frameworks, the retained organic species generated in the catalysts during the MTO reaction are influenced by both their sizes and amounts. A detailed analysis of the confined organic species showed the formation of MCP with varied methyl substitutions over the three zeolites. 12C/13C-methanol switch experiments were employed to investigate the reaction route for product generation. The differences in the participation levels of the methylbenzene and methylcyclopentadiene over the three zeolite catalysts imply that the formation and function of the organic species formed in the 10-membered ring channel were impacted by the chemical environment of the zeolites, and the methanol conversion that occurred in the 10-membered ring channels of the three zeolites also followed different reaction routes.

Zr incorporated Zn-Al dehydrated hydrotalcites solid bases were obtained by calcining Zr-Zn-Al hydrotalcites at 140 °C and 200 °C. These solid bases were characterized by X-ray diffraction, N 2 adsorption/desorption, UV–vis diffuse reflectance spectra, temperature programmed desorption of CO 2 and infrared spectroscopy of CO 2 adsorption. The results show that the Zr incorporated Zn-Al dehydrated hydrotalcites have larger pore diameter and stronger base-strength than the un-incorporated one. The sample with the Zr/Zn/Al ratio of 0.25/2.56/1 has the largest pore diameter, which is 10.6 nm. The basic sites of these solid bases are OH groups and the sample treated at 200 °C has more basic sites than which treated at 140 °C. These solid bases were evaluated as catalysts in the transesterification reaction for the biodiesel (FAME) production. The sample (with Zr/Zn/Al of 0.25/2.56/1) treated at 200 °C gives the FAME yield of 91.71% at 140 °C, 1.7 MPa and 1.0 h −1 . It shows no deactivation in the reaction of about 300 h.

A single-step hydrotreatment of vegetable oil to produce high quality diesel-ranged alkanes over Ni/zeolite catalyst is devised. The Ni/zeolite catalysts prepared by incipient wetness impregnation method using SAPO-11, ZSM-5, ZSM-22, ZSM-23 and Beta zeolites as supports are evaluated in this single-step hydrotreatment process. The effects of the support and the metal loading amount are studied from the catalytic performance and characterization results obtained by techniques such as XRD, Physisorption, NH3-TPD and Pyridine-IR. Over the 8 wt%Ni/SAPO-11 catalyst, 100% conversion of soybean oil is obtained at 370 degrees C, 4 MPa and 1 h(-1), with an organic liquid yield of 74.8% which is nearly 90% of the maximum theoretical liquid yield. In the organic products, the alkane selectivity is 100%, and more than 85% isomerization selectivity is achieved. In order to learn the detailed scheme of the single-step hydrotreatment process, the intermediates have been analyzed from which reaction pathways are proposed and discussed. (C) 2014 Elsevier B.V. All rights reserved.

The transesterification of soybean oil with methanol to biodiesel using lanthanum doped zinc aluminate with spinel structure as catalyst is studied. The catalyst was characterized by X-ray diffraction (XRD), N-2 adsorption/desorption, temperature programmed desorption of CO2 (CO2-TPD) and infrared spectroscopy of CO2 adsorption (CO2-IR). The results of CO2-IR show that the basic sites of La doped zinc aluminate are surface isolated O2- anions and OH- groups. The results of CO2-TPD show that the total amount of basic sties of the catalyst improves with the increase of the La doping amount until which is to 18.5 wt%. Doping La also enlarges the pore volume and diameter of zinc aluminate. It gets the largest pore volume (0.30 cm(3) g(-1)) and pore diameter (7.9 nm) when doped with 5.5 wt% La. Zinc aluminate doped with 5.5 wt% La (5.5% La/ZnAl2O4) exhibits the highest activity, with which the biodiesel yield exceeds 95% at 160 degrees C, 2.0 MPa and 0.9h(-1). Furthermore, the transesterification reaction of about 500h in a fixed-bed reactor was carried out over 5.5% La/ZnAl2O4 catalyst. No deactivation and leaching of catalyst components were happened on the catalyst in reaction. (C) 2013 Elsevier B.V. All rights reserved.

A series of Ce-modified Raney Ni (RNi) catalysts were successfully prepared by a simple wet chemical route and employed in aqueous-phase reforming of cellulose. Remarkable enhancement in hydrogen selectivity and yield after the Ce introduction was observed. At 533 K and autogenous pressure, a highest hydrogen yield of 17.8 mmol/gcellulose, which was comparable with that of 5 wt% Pt/AC, could be obtained over Ce-modified catalyst at a Ce:Ni ratio of 0.054. The catalysts were characterized by N2 adsorption/desorption, XRD, SEM, XPS and H2-TPD. It was found that cerium existed at the surface of the catalyst as Ce(OH)3, and more defects were generated during Ce modification. Based on the characterization and catalytic performance, it was suggested that the deposited Ce(OH)3 may transform into reducible CeO2 under the reaction conditions, thus promoting the desired water–gas shift reaction, leading to more H2. On the other hand, the active sites for undesired methanation reaction may be effectively poisoned by Ce modification, thus leading to less undesired methane. Addition of Ce to Raney Ni catalysts could significantly enhance the hydrogen selectivity and yield for aqueous-phase reforming of cellulose, while correspondingly suppressing the methanation reaction. A highest hydrogen yield of 17.8 mmol/gcellulose, which was comparable with that of 5 wt% Pt/AC, could be obtained at a Ce:Ni ratio of 0.054.

A one-step hydrotreatment of vegetable oil combining deoxygenation and isomerization to directly produce low cloud point, high quality diesel is devised. The Pt/zeolite bifunctional catalysts prepared by using SAPO-11 and ZSM-22 zeolites as supports are used in this process. Catalytic reactions are conducted in a fixed-bed reactor under a hydrogen atmosphere. Over the bifunctional catalyst, 100?% conversion of soybean oil is obtained at 357?degrees C, 4 MPa, and 1 h-1, and 80?% organic liquid yield is achieved, which is close to the maximum theoretical liquid yield. In the organic products, the alkanes selectivity is 100?% with an i-alkanes selectivity above 63?%. NH3-temperature programmed desorption (TPD), pyridine IR spectroscopy, and other characterization techniques are used to study the effect of the support acidity on the reaction pathway. Over the Pt/zeolite bifunctional catalyst with less strong Lewis acid sites, the reaction proceeds via the decarboxylation plus decarbonylation pathway. This one-step method provides a new strategy to produce low cloud point, high quality diesel from biomass feedstock in a more economic and attractive way. (c) 2012 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim