A highly active and selective silver on nickel fiber catalyst was successfully prepared for selective oxidation of benzyl alcohol. The Ag/Ni catalyst was obtained by loading Ag (10 wt%) on paper-like microfibrous structure (consisting of 5 vol% of 8- m Ni-fiber) by impregnation method. The wettability of Ni-fiber support was vastly improved by a simple water pre-wetting and overnight drying treatment process. This yielded a catalyst (Ag/Ni-fiber-M) with more Ag cations and selectively active oxygen species than the catalyst (Ag/Ni-fiber) using the untreated support. The Ag/Ni-fiber-M showed much higher lowtemperature activity/selectivity than the Ag/Ni-fiber, which could be attributed to the differences in their silver morphology and particle size. The best conversion and benzaldehyde selectivity observed were both 97% for Ag/Ni-fiber-M at 300 ◦C, and 91 and 84% for Ag/Ni-fiber at 380 ◦C, respectively. Benzyl alcohol selective oxidation would proceed concurrently through both directO2 activation route and NiOxparticipating oxygen spillover route. Formation of NixC phase occurred and hampered the latter reaction route thereby leading to partial deactivation. However, spent catalyst could restore activity through an oxidation treatment at 400 ◦C.

An aerobic oxidative removal of mercaptans from gasoline in the absence of liquid base has been demonstrated for gasoline sweetening over CuZnAl catalyst. This process could proceed at large WHSV of gasoline (50–70 h 1) with [95% mercaptan conversion at 150 C (or 300 C) using an O2/S molar ratio of 20–40. At 150 C, dimerization of mercaptans occurred dominantly to form their disulfides. At 300 C, deep oxidation of the mercaptans to SO2 was the dominant process in the first tens of hours, but it decreased then with prolonged time on stream and meanwhile the dimerization increased. The spent catalyst could be restored to its fresh activity level only through a calcination treatment in air. This process was also demonstrated to be ffective and efficient for sweetening of a real cracking gasoline.

A non-woven microfibrous thin-sheet structure with 5 vol% 8 lm diameter nickel fibers was built up using wet-lay papermaking and sintering process. Silver was then placed onto the sinter-locked Ni-fiber by the incipient wetness impregnation with AgNO3 aqueous solution. As-made Ag/Ni-fiber catalysts exhibited much higher activity/selectivity for the gas-phase selective oxidation of benzyl alcohol to benzaldehyde, and provided significant increase in the steady-state volumetric reaction rate with dramatic saving of Ag, in comparison with the electrolytic silver and Ag/a-Al2O3 catalysts. Conversion of 84% as achievable with benzaldehyde selectivity of 94% at 380 C using a high WHSV of 30 h 1.

A series of CuZnAl oxide-composite catalysts were prepared via ecomposition of CuZnAl hydrotalcite-like compounds (HTLcs). The catalysts derived from CuZnAl HTLcs (Cu: 37%, Zn: 15%, Al: 48% mol; using metal nitrate or acetate precursors) at 600 C provided excellent activity and stability for the methanol steam reforming. CuZnAl HTLcs were almost decomposed completely at 600 C to form highly dispersed CuO with large specific surface area while forming CuAl2O4 spinel that played a key role in separating and stabilizing the nano-sized Cu and ZnO during the reaction. The CuZnAl catalyst prepared from metal acetates could highly convert H2O/MeOH (1.3/1, mol/mol) mixture into hydrogen with only 0.05% CO at 250 C or 0.005% at 210 C. It is videnced that the former afforded stronger Cu-ZnO interaction, which might be the intrinsic reason for the significant promotion of catalyst electivity. VVC 2009 American Institute of Chemical Engineers AIChE J, 55: 1217-1228, 2009

Pt/CeO2–Al2O3 catalysts with and without Gd2O3 additive were prepared by stepwise incipient wetness impregnation (IWI) method. The catalysts were tested for autothermal reforming (ATR) of retail gasoline containing 158–500 ppm sulfur under the optimal reaction conditions: 800 8C, gasoline WHSV of 0.9 h 1 and aH2O/O2/Cmolar ratio of 5/0.35/1. It is foundthat the content ofGd2O3 and impregnationprocedure for catalyst preparation significantly affected the catalyst performance. Pt catalyst supported on the Al2O3 that was pre-impregnated with Ce and Gd nitrates orderly to 15 wt% CeO2 and 1.6 wt% Gd2O3 was the best catalyst forATRof gasoline with high reactivity and excellent stability. Within 1000-h ATRof retail asoline over this catalyst, gasoline conversion was slowly decreased to 95% after 300-h run and then remained at 95% throughout the test, while H2 fraction in reformate remained at 67% with a CH4 fraction less than 0.6%. It is revealed that modification of Al2O3 with CeO2 first and Gd2O3 then endowed the produced Pt catalyst withmany advantageous effects such as significantly improved and stabilized Pt-CeO2 interaction, greatly attenuated Pt-sintering, and enhanced oxygen ion conductivity of bulk CeO2.

A miniature ammonia cracker, with an overall weight of z195 g and volume of z50 cm3, has been developed for portable fuel cell power supply. The cracker is composed of a SS-316L tube body, a heating rod and monolithic microfibrous CeO2-promoted Ni/Al2O3 catalysts incorporated within the annular housings between the heating rod and the inner wall of the tubular body. The catalyst monolith is obtained by placing CeO2 and Ni onto the microfibrous carrier consisting of 3.5 vol% 8 mm diameter nickel fibers and 38 vol% 100–200 mm Al2O3 particulates through stepwise incipient wetness impregnation method using cerium and nickel nitrate precursors. This cracker shows pleasing operability for high efficiency H2 production via ammonia cracking with low pressure drop. Roughly 158Wequivalents of H2 can be produced with ammonia conversion of >99.9% at 600C and 1100 standard cubic centimeter per minute (sccm) ammonia feed gas rate within this cracker through the entire 300 h test. Power density and energy density are estimated to be z3160 W/L and z2150 Wh/kg, respectively.

Y.L. gratefully thanks the Program for New Century Excellent Talents in University (06-NCET-0423), Shuguang Project (06SG28), and Shanghai Leading Academic Discipline Project (B409). This work was supportedby the National Natural Science Foundation of China (20590366, 20570360), the Ministry of Science andT echnology of China (2007AA05Z101), andthe Science & Technology Commission of Shanghai Municipality (06SR07101, 06 JC14023).

A sulfur-tolerant Pt catalyst has been developed for fuel processors being developed for use with fuel cells, using a fluorite-type Ce0.8Gd0.2O1.9 support. The catalyst calcination temperature is crucial to ensure the maintenance of sulfur tolerance. The catalyst calcined at 800 ◦C retained its activity and selectivity for entire 100-h test period in the steam reforming of iso-octane with 300 μg/g of sulfur, whereas the catalyst calcined at 600 ◦C obviously lost activity in this course. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for CO and CO/H2S adsorption was performed to characterize the nature of the Pt sites and to evaluate their ability to tolerate sulfur. Strongly electron- eficient Pt sites, evidenced by a CO adsorption band at νmax 2104-2108 cm−1, were immune to sulfur poisoning and were uniformly formed with the alcination at 800◦C. In addition, thiophene sulfur was completely converted into H2S and likely complied with a redox mechanism.

A novel microfibrous composite bed reactor was developed and was demonstrated for high efficiency hydrogen production by the decomposition of ammonia at moderate temperatures in portable fuel cell power system applications. By using a high-speed and low-cost papermaking technology combined with a subsequent sintering process, sinter-locked three-dimensional microfibrous networks consisting of y3 vol% 8 mm (dia.) nickel microfibers were utilized to entrap y35 vol% 100-200 mm dia. porous Al2O3 support particulates. A CeO2 promoter and active Ni component were then dispersed onto the pore surface of the entrapped Al2O3 support particulates by a stepwise incipient wetness impregnation method. The microfibrous structure took advantage of a large void volume, entirely open structure, high heat/mass transfer, high permeability, good thermal stability, and unique form factors. Addition of ceria significantly promoted the low-temperature activity of Ni/Al2O3 catalyst particulates incorporated into the micorfibrous structure. The use of fine particles of catalyst significantly attenuated the intraparticle mass transport limitations. As a result, the present novel microfibrous composite bed reactor provided excellent activity and structure stability in ammonia decomposition, as ell as low pressure drop and high efficiency reactor design. At a 90% onversion of a 145 sccm ammonia feed rate, the microfibrous entrapped Ni/CeO2–Al2O3 catalyst composite bed could provide a 4-fold reduction of catalytic bed volume and a 5-fold reduction of catalytic bed weight (or 9-fold reduction of catalyst dosage), while leading to a reduction of reaction temperature of 100 uC, compared to a packed bed with 2 mm dia. Ni/CeO2–Al2O3 catalyst pellets. This composite bed was capable of producing roughly 22 W of hydrogen power, with an ammonia conversion of 99% at 600 uC in a bed volume of 0.5 cm3 throughout a 100 h continuous test. These initial and promising results established that the microfibrous nickel-based catalyst composites were effective for high efficiency production of hydrogen by ammonia decomposition, while achieving a significant reduction of overall catalytic bed weight and volume. We anticipate our assay to be a new point for small-scale hydrogen production, where the microfibrous catalytic reactors considered in isolation can satisfy several of the most fundamental riteria needed for useful operation.

A non-woven microfibrous structure with 15 vol% 8 mm diameter nickel fibers was built using wet-lay papermaking and sintering processes. Surface of the sinter-locked nickel fibers was then chemically modified with Al2O3 and CeO2, by immersing this novel microfibrous metallic media in a 65 8C aqueous solution containing each of Al(NO3)3 6H2O and Ce(NO3)3 6H2O or both of them for 2 or 4 h at a constant metal ion concentration of 0.5 mol/L. Chemical modifications provided a significant increase of the surface ickel atoms per gram catalyst but obviously suppressed the activity of the metallic nickel sites as indicated by the lowered TOF values. The chemical modification with a mixture solution with the optimal Al3+/Ce3+ ratio of 9 resulted in a 10-fold increase of the surface nickel atoms per gram atalyst but a 3-fold decrease of the TOF of ammonia, compared with the neat microfibrous nickel substrate. This chemically modified catalyst was apable of producing roughly 20 Wpower hydrogen with >99% ammonia conversion at 650 8C in a bed of 0.9 mL throughout a 100 h continuous test. Activation ergies (Ea) for microfibrous nickel catalysts were all alike in range from 103 to 105 kJ/mol, suggesting that the active site nature was not changed by the chemical modification treatments.