Al2O3负载Cu,Fe或Ni掺杂氧化钼催化乙苯氧化脱氢（英文）

Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.     

Cu,Fe, or Ni doped molybdenum oxide supported on Al2O3 for the oxidative dehydrogenation of ethylbenzene

Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an u...     

镧-镍复合氧化物纳米微粒的固相合成及其催化性能

The La-Ni complex oxide catalyst was prepared by solid state reactions under microwave. The structure and reducibility of the catalyst were characterized by using TG-DTA, XRD, TEM and TPR methods. At the same time the catalytic activity of oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide over the complex oxide nanoparticle was investigated.The Results show that the product is K2NiF4 nanoparticles,and the size is 13nm.The complex oxide sample had high activity for the oxidative dehydrogenation of ethylbenzene to styrene.     

Synthesis of 2-methylpyrazine from cyclocondensation of ethylene diamine and propylene glycol over promoted copper catalyst

The 2-methylpyrazine was synthesized by catalytic reaction of ethylene diamine and propylene glycol at 380 ℃. The alumina supported copper catalysts with promoter were prepared by impregnation method, characterized by ICP-AES, BET and TPR. The results demonstrated that the dehydrogenation was improved by addition of chromium promoter. The selectivity of 2-methylpyrazine reached 84.75%, while the conversions of reactants were also enhanced.     

Effect of support modification on the characterization and catalytic activity of Mo/Al_2O_3 catalysts

Molybdenum catalysts(15 wt% Mo O3loading) supported on alumina,alumina–magnesia,and alumina–chromia were prepared via impregnation technique and studied for the reaction of methyl-cyclohexane dehydrogenation. The catalysts were evaluated by means of FT-IR,XRD,DSC,TPR,and N2adsorption–desorption isotherms. The results clarified that Mo/alumina–magnesia catalyst possesses small crystallite size and high surface area(240 m2/g) and is selective toward the formation of dehydrogenated product(96.5%). The yield to ring-opening products is higher on Mo/alumina–chromia catalyst due to its higher acidity and larger metal crystals,which favor the ring-opening reaction and lower metallic activity with selectivity toward ringopening products(32%).     

Novel Carbon Nanotubes-supported NiB Amorphors Alloy Catalyst for Benzene Hydrogenation

The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina.     

Investigation on the Performance of Supported Molybdenum Carbide for the Partial Oxidation of Methane

The performance of uspported and unsupported molybdenum carbide for the partial oxidation of methane (POM) to syngas was investgated.An evaluation of the catalysts indicates that bulk molybdenum carbied has a higher methane conversion during the initial stage but a lower selectivity to CO and H2/CO ratio in the products.The rapid deactivation of the catalyst is also a significant problem.However,the supported molybdenum carbide catalyst shows a much higher methane conversion,increased selectivity and significantly improved catalytic stability.The characterization by XRD and BET specific area measurements depict an improved dispersion of molybdenum carbide when using alumina as a carrier.The bulk or the supported molybdenum carbide exists in the β-Mo2C phase,while it is transformed into molybdenum dioxide postcatalysis which is an improtant cause of molybdenum carbide deactivation.     

Zn-Co bimetallic supported ZSM-5 catalyst for phosgene-free synthesis of hexamethylene–1,6–diisocyanate by thermal decomposition of hexamethylene–1,6–dicarbamate

A set of mono-and bimetallic(Zn-Co) supported ZSM-5 catalysts was first prepared by PEG-additive method. The physicochemical properties of the catalysts were investigated by FTIR, XPS, XRD, N_2adsorption-desorption measurements, SEM, EDS and NH3-TPD techniques. The physicochemical properties showed that the Zn Co_2O_4 spinel oxide was formed on the ZSM-5 support and provided effectual synergetic effect between Zn and Co species for the bimetallic catalyst. Furthermore, bimetallic supported ZSM-5 catalyst exhibited weak, moderate and strong acidic sites, while the monometallic supported ZSM-5 catalyst showed only weak and moderate or strong acidic sites. Their catalytic performances for thermal decomposition of hexamethylene–1,6–dicarbamate(HDC) to hexamethylene–1,6–diisocyanate(HDI) were then studied. It was found that the bimetallic supported ZSM-5 catalysts,especially Zn-2Co/ZSM-5 catalyst showed excellent catalytic performance due to the good synergetic effect between Co and Zn species, which provided a suitable contribution of acidic sites. HDC conversion of 100% with HDI selectivity of 91.2% and by-products selectivity of 1.3% could be achieved within short reaction time of 2.5 h over Zn-2Co/ZSM-5 catalyst.     

MECHANISTIC STUDIES ON CATALYTIC DEHYDROGENATION OF ETHYL-BENZENE OVER IRON-OXIDE-BASED CATALYST SYSTEMS-I. ROLE OF LATTICE OXYGEN

The role of lattice oxygen in the catalytic dehydrogenation of ethylbenzene over industrial iron-oxide-based catalysts has been investigated mainly by means of isotopic exchanges attending the dehydrogenation reaction.The results indicated that although the exchange of lattice oxygen with steam oxygen appeared to take place to an appreciable extent,the direct catalytic dehydrogenation of ethylbenzene appeared to be the major reaction pathway,with catalytic dehydrogenation by oxygen-transfer reaction pathway playing only a minor role,as revealed different extents of hydrogeh-deute-rium isotopic exchange between ethylbenzene and steam D2Q at low and very high space velocities.The mechanisms of these two reaction pathways are discussed.For the oxygen-transfer dehydrogenation mechanism,electron transport between neighboring Active-sites operating cooperatively in opposite phases of their redox cycles may be a requisite factor.     

负载型钌催化剂催化山梨醇氢解制乙二醇(英)

Supported Ru catalysts were prepared by wet impregnation to evaluate the role of different oxide supports（Al₂O₃,SiO₂,TiO₂,ZrO₂） in sorbitol hydrogenolysis to glycols.X-ray diffraction,transmission electron microscopy,hydrogen chemisorption,X-ray photoelectron spectroscopy,and NH3temperature-programmed desorption were used to characterize the catalysts,which were active in the hydrogenolysis of sorbitol.The support affected both the physicochemical properties and catalytic behavior of the supported Ru particles.The characterization results revealed that the Ru/Al₂O₃catalyst has a high surface acidity,partially oxidized Ru species on the surface,and a higher surface Ru/Al atomic ratio,which gave it the highest selectivity and yield to glycols.     

Selective oxidation of ethane to aldehydes over SBA-15 supported molybdenum catalyst

SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsorption-desorption, XRD, TEM, UV-Vis, Raman, XANES and H2-TPR. The results showed that a trace amount of MoO3 was produced on high Mo content samples. Tum-over frequency （TOF） and product selectivity are dependent on the molybdenum content. Both Mo0.75/SBA-15 and Mo1.75/SBA-15 catalysts give the higher catalytic activity and the selectivity to the total aldehydes for the selective oxidation of C2H6. At the reaction temperature of 625℃, the maximum yield of aldehydes reached 4.2% over Mo0.75/SBA-15 catalyst. The improvement of the activity and selectivity was related with the state of MoOx species.     

Low-temperature hydrogenation of maleic anhydride to succinic anhydride and γ-butyrolactone over pseudo-boehmite derived alumina supported metal(metal = Cu,Co and Ni) catalysts

The pseudo-boehmite derived alumina supported metal(Cu,Co and Ni) catalysts prepared by the impregnation method were investigated in hydrogenation of maleic anhydride(MA) to succinic anhydride(SA) and γ-butyrolactone.The catalysts were characterized by ICP-AES,N_2 adsorptiondesorption,XRD,H_2-TPR,CO-TPD,dissociative N_2O adsorption and TEM and the results showed that the alumina possessed mesoporous feature and the metal species were well dispersed on the support.Compared to Cu/Al_2O_3 and Co/Al_2O_3,Ni/Al_2O_3 exhibited higher catalytic activity in the MA hydrogenation with 92%selectivity to SA and nearly 100%conversion of MA at 140 °C under 0.5 MPa of H_2 with a weighted hourly space velocity of 2 h ~1(MA).The stability of Ni/Al_2O_3 catalyst was also investigated.     

Characterization and reactivity of γ-Al_2O_3 supported Pd–Ni bimetallic nanocatalysts for selective hydrogenation of cyclopentadiene

Several g-Al2O3 supported Pd–Ni bimetallic nanocatalysts(Pd–Ni(x:y)/Al2O3; where x and y represent the mass ratio of Pd and Ni, respectively) were prepared by the impregnation method and used for selective hydrogenation of cyclopentadiene to cyclopentene. The Pd–Ni/Al2O3 samples were confirmed to generate Pd–Ni bimetallic nanoparticles by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). The catalytic activity was assessed in view of the effects of different mass ratios of Pd and Ni, temperature, pressure, etc. Among all the samples, the Pd–Ni(1:1)/Al2O3(PN-1:1) catalyst showed extremely high catalytic ability. The conversion of cyclopentadiene and selectivity for cyclopentene can be simultaneously more than 90%.     

Preparation of hierarchical mesoporous Zn/HZSM-5 catalyst and its application in MTG reaction

The hierarchical mesoporous Zn/ZSM-5 zeolite catalyst was prepared by NaOH treatment and Zn impregnation, and its application in the conversion of methanol to gasoline (MTG) was studied. N2 adsorption-desorption results showed that the mesopores with sizes of 2–20 nm in HZ5/0.3AT was formed by 0.3 M NaOH alkali treatment. The zeolite samples after modification were also characterized by XRF, AAS, XRD, SEM and NH3-TPD methods. Zn impregnated catalyst Zn/HZ5/0.3AT exhibited dramatic improvements in catalytic lifetime and liquid hydrocarbons yield. The selectivity of aromatic hydrocarbons was also improved after Zn impregnation. It is suggested that the mesopores of Zn/HZ5/0.3AT enhanced the synergetic effect of Zn species and acid sites and the capability to coke tolerance, which were confirmed by the results of catalytic test and TGA analysis, respectively.     

Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101: Insight into chromium species on activity and selectivity

Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCr Al-I1 with largest specific surface area of 198 m2 g-1prepared with aluminium isopropoxide(Al(i-OC3H7)3) by ultrasonic impregnation method. However, the catalyst KCr Al-I2 synthesized by stirring impregnation possessed crystalline α-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich Crx Al2-xO3 solid solutions, designated as Cr Al-I and Cr Al-II phase, were formed over the catalysts KCr Al-I3(prepared by Al(i-OC3H7)3with nitric acid regulation), KCr Al-C4(prepared by aluminium chloride hexahydrate) and KCr Al-N5(prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCr Al-I1 exhibited the high isobutane conversion due to its highly dispersed chromium species. However, KCr Al-I3, KCr Al-C4 and KCr Al-N5 showed the higher isobutene selectivity(95.2%-96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.     

Cobalt supported on CNTs-covered γ-and nano-structured alumina catalysts utilized for wax selective Fischer-Tropsch synthesis

Cobalt supported on carbon nanotubes(CNTs)-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis(FTS).Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications.In this investigation regularγ-and nano-structured(N-S)alumina as well as CNTs-covered regularγ-and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru.The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS.γ-Al2O3 was prepared by calcination of bohemite and N-S-Al2O3 was prepared by sol-gel method using aluminum chloride as starting material.Catalyst evaluations indicated that N-S-Al2O3 was superior to regularγ-Al2O3 and that CNTs-covered alumina supports were favored over non-covered ones in terms of activity and heavy hydrocarbon selectivity.These were justified by porosimetric characteristics of the catalysts and existence of CNTs points of view. CNTs-covered catalysts also showed higher wax selectivity and better resistance to deactivation.Furthermore,TPR analysis indicated that the cobalt aluminate phase,which is responsible for the permanent deactivation of alumina supported Co-based catalysts,did not form on alumina supported Co-based catalysts covered with CNTs due to weaker interactions between cobalt and alumina.     

Production of hydrogen-rich gas and multi-walled carbon nanotubes from ethanol decomposition over molybdenum modified Ni/MgO catalysts

A series of molybdenum modified Ni/MgO catalysts(Ni-Mo/MgO) with different loading ratios of Ni : Mo were prepared by impregnation method. Ethanol decomposition to co-produce multi-walled carbon nanotubes and hydrogen-rich gas at temperatures of 600–800 ℃ was investigated over the synthesized Ni-Mo/MgO catalysts. The results showed that the catalytic activity depended strongly on the reaction temperature and loading ratio of Ni : Mo. According to the gaseous and solid products obtained, the reaction pathways for ethanol decomposition were suggested.     

Production of hydrogen-rich gas and multi-walled carbon nanotubes from ethanol decomposition over molybdenum modified Ni/MgO catalysts

A series of molybdenum modified Ni/MgO catalysts(Ni-Mo/MgO) with different loading ratios of Ni : Mo were prepared by impregnation method. Ethanol decomposition to co-produce multi-walled carbon nanotubes and hydrogen-rich gas at temperatures of 600–800 ℃ was investigated over the synthesized Ni-Mo/MgO catalysts. The results showed that the catalytic activity depended strongly on the reaction temperature and loading ratio of Ni : Mo. According to the gaseous and solid products obtained, the reaction pathways for ethanol decomposition were suggested.     

Effects of impregnation sequence on the microstructure and performances of Cu-Co based catalysts for the synthesis of higher alcohols

Silica-supported CuCo catalysts were prepared by impregnation method with different impregnation sequence for higher alcohols synthesis. These catalysts were characterized by H2-TPR, XRD, N2 adsorption, XPS techniques and CO selective hydrogenation reaction measurement. The effects of impregnation sequence on the structure and performance of catalysts were investigated, and there were important influences on the selectivity to higher alcohols. There was a strong synergistic effect between copper and cobalt for the co-impregnated sample. The CuCo/SiO2 catalyst prepared by co- impregnation showed a better yield of total alcohols, and a higher selectivity to total alcohols which reached 51.5%.     

Cr-free Co-Cu/SBA-15 catalysts for hydrogenation of biomass-derivedα-,β-unsaturated aldehyde to alcohol

Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of bio-mass-derived α-, β-unsaturated aldehyde (furfural) to value-added chemical furfuryl alcohol (FOL). Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings (2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray dif-fraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, ener-gy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemi-sorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the cata-lyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.