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Chinese Journal of Catalysis
2017, Vol. 38, No. 1
Online: 18 January 2017

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Table of Contents for VOL.38 No.1 2017, 38 (1):  0-0.  Abstract ( 242 )   PDF (1441KB) ( 668 )

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Co2C nanoprisms for syngas conversion to lower olefins with high selectivity Yunjie Ding 2017, 38 (1):  1-4.  Abstract ( 719 )   [Full Text(HTML)] () PDF (539KB) ( 965 )

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Latest progress in hydrogen production from solar water splitting via photocatalysis, photoelectrochemical, and photovoltaic-photoelectrochemical solutions Rengui Li 2017, 38 (1):  5-12.  DOI: 10.1016/S1872-2067(16)62552-4 Abstract ( 1409 )   [Full Text(HTML)] () PDF (933KB) ( 2764 )   Hydrogen production via solar water splitting is regarded as one of the most promising ways to utilize solar energy and has attracted more and more attention. Great progress has been made on photocatalytic water splitting for hydrogen production in the past few years. This review summa-rizes the very recent progress (mainly in the last 2-3 years) on three major types of solar hydrogen production systems:particulate photocatalysis (PC) systems, photoelectrochemical (PEC) systems, and photovoltaic-photoelectrochemical (PV-PEC) hybrid systems. The solar-to-hydrogen (STH) conversion efficiency of PC systems has recently exceeded 1.0% using a SrTiO3:La,Rh/Au/BiVO4:Mo photocatalyst, 2.5% for PEC water splitting on a tantalum nitride photoanode, and reached 22.4% for PV-PEC water splitting using a multi-junction GaInP/GaAs/Ge cell and Ni electrode hybrid sys-tem. The advantages and disadvantages of these systems for hydrogen production via solar water splitting, especially for their potential demonstration and application in the future, are briefly de-scribed and discussed. Finally, the challenges and opportunities for solar water splitting solutions are also forecasted.

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Construction of an operando dual-beam fourier transform infrared spectrometer and its application in the observation of isobutene reactions over nano-sized HZSM-5 zeolite Jiaxu Liu, Jilei Wang, Wei Zhou, Cuilan Miao, Guang Xiong, Qin Xin, Hongchen Guo 2017, 38 (1):  13-19.  DOI: 10.1016/S1872-2067(17)62751-7 Abstract ( 439 )   [Full Text(HTML)] () PDF (637KB) ( 940 )   An operando dual-beam Fourier transform infrared (DB-FTIR) spectrometer was successfully de-veloped using a facile method. The DB-FTIR spectrometer is suitable for the real-time study of the dynamic surface processes involved in gas/solid heterogeneous catalysis under real reaction condi-tions because it can simultaneously collect reference and sample spectra. The influence of gas-phase molecular vibration and heat irradiation at real reaction temperatures can therefore be eliminated. The DB-FTIR spectrometer was successfully used to follow the transformation of isobutene over nano-sized HZSM-5 zeolite under real reaction conditions.

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Efficient removal of ammonia with a novel graphene-supported BiFeO3 as a reusable photocatalyst under visible light Congyang Zou, Shouqing Liu, Zhemin Shen, Yuan Zhang, Nishan Jiang, Wenchao Ji 2017, 38 (1):  20-28.  DOI: 10.1016/S1872-2067(17)62752-9 Abstract ( 518 )   [Full Text(HTML)] () PDF (948KB) ( 1241 )   Graphene-supported BiFeO3 (rG-BiFeO3) was synthesized by the hydrothermal method and used for the efficient removal of ammonia under visible light. X-ray diffraction, transmission electron mi-croscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy were conducted to characterize the rG-BiFeO3. The specific surface area of the rG-BiFeO3 catalyst was 48.6 m2/g, larger than that of BiFeO3 (21.0 m2/g). When used as a heterogeneous photocatalyst, rG-BiFeO3 achieved 91.20% degradation of a NH3-N solution (50 mg/L) at pH=11 under visible-light irradiation in the absence of hydrogen peroxide. The degrada-tion of ammonia followed pseudo-first-order kinetics, and the catalyst retained high photocatalytic activity after seven reaction cycles. Study of the mechanism showed that the holes, superoxide ani-on radicals, and hydroxyl radicals, arising from the synergy between graphene and BiFeO3, oxidized NH3 directly to N2.

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Fabrication of highly dispersed platinum-deposited porous g-C3N4 by a simple in situ photoreduction strategy and their excellent visible light photocatalytic activity toward aqueous 4-fluorophenol degradation Zhenxing Zeng, Kexin Li, Kai Wei, Yuhua Dai, Liushui Yan, Huiqin Guo, Xubiao Luo 2017, 38 (1):  29-38.  DOI: 10.1016/S1872-2067(16)62589-5 Abstract ( 390 )   [Full Text(HTML)] () PDF (1343KB) ( 1030 )   A series of highly dispersed platinum-deposited porous g-C3N4 (Pt/pg-C3N4) were successfully fab-ricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g-C3N4 as precursors. Porous g-C3N4 was fabricated by a pretreatment strategy using melamine as a raw ma-terial. The morphology, porosity, phase, chemical structure, and optical and electronic properties of as-prepared Pt/pg-C3N4 were characterized. The photocatalytic activity of as-prepared Pt/pg-C3N4 was preliminarily evaluated by the degradation of aqueous azo dyes methyl orange under visible light irradiation. The as-prepared Pt/pg-C3N4 were further applied to the degradation and mineral-ization of aqueous 4-fluorophenol. The recyclability of Pt/pg-C3N4 was evaluated under four con-secutive photocatalytic runs.

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La-doped Pt/TiO2 as an efficient catalyst for room temperature oxidation of low concentration HCHO Honggen Peng, Jiawei Ying, Jingyan Zhang, Xianhua Zhang, Cheng Peng, Cheng Rao, Wenming Liu, Ning Zhang, Xiang Wang 2017, 38 (1):  39-47.  DOI: 10.1016/S1872-2067(16)62532-9 Abstract ( 760 )   [Full Text(HTML)] () PDF (1008KB) ( 1305 )   Catalytic oxidation of formaldehyde (HCHO) is the most efficient way to purify indoor air of HCHO pollutant. This work investigated rare earth La-doped Pt/TiO2 for low concentration HCHO oxida-tion at room temperature. La-doped Pt/TiO2 had a dramatically promoted catalytic performance for HCHO oxidation. The reasons for the La promotion effect were investigated by N2 adsorption, X-ray diffraction, CO chemisorption, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and high-angle annular dark field scanning TEM. The Pt nanoparticle size was reduced to 1.7 nm from 2.2 nm after modification by La, which led to higher Pt dispersion, more exposed active sites and enhanced metal-support interaction. Thus a superior activity for indoor low concentration HCHO oxidation was obtained. Moreover, the La-doped TiO2 can be wash-coated on a cordierite monolith so that very low amounts of Pt (0.01 wt%) can be used. The catalyst was evaluated in a simulated indoor HCHO elimination environment and displayed high purifying efficiency and stabil-ity. It can be potentially used as a commercial catalyst for indoor HCHO elimination.

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One-step post-synthesis treatment for preparing hydrothermally stable hierarchically porous ZSM-5 Jian Ding, Teng Xue, Haihong Wu, Mingyuan He 2017, 38 (1):  48-57.  DOI: 10.1016/S1872-2067(16)62549-4 Abstract ( 489 )   [Full Text(HTML)] () PDF (1003KB) ( 1210 )   Hierarchically porous ZSM-5 (SiO2/Al2O3≈120) containing phosphorus was prepared by a one-step post-synthesis treatment involving controlled desilication and phosphorous modification. The hier-archically porous ZSM-5 featured high thermal and hydrothermal stability. The obtained ZSM-5 zeolites were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption, NH3 temperature-programmed de-sorption, and 27Al and 31P magic-angle spinning nuclear magnetic resonance spectroscopy. The prepared ZSM-5 displayed enhanced activity and prolonged lifetime toward hydrocarbon cracking. The high activity was attributed to improved coke tolerance owing to the presence of the highly stable mesoporous network of ZSM-5 and acid sites introduced upon phosphorus modification. Additionally a mechanism of the stabilization of the zeolites by phosphorus was proposed and dis-cussed.

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One-pot conversion of cyclohexanol to ε-caprolactam using a multifunctional Na2WO4-acidic ionic liquid catalytic system Hefang Wang, Liyuan Ji, Rongbin Hu, Meidan Gao, Yanji Wang 2017, 38 (1):  58-64.  DOI: 10.1016/S1872-2067(16)62563-9 Abstract ( 422 )   [Full Text(HTML)] () PDF (535KB) ( 987 )   Na2WO4-acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic sys-tem for the one-pot conversion of cyclohexanol to ε-caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid-functionalized ionic liquids with HSO4- as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase-transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate during the oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rear-rangement.

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Gas-phase epoxidation of propylene by molecular oxygen over Ag-Cu-Cl/BaCO3 catalyst: Effects of Cu and Cl loadings Qing Zhang, Yanglong Guo, Wangcheng Zhan, Yun Guo, Li Wang, Yunsong Wang, Guanzhong Lu 2017, 38 (1):  65-72.  DOI: 10.1016/S1872-2067(16)62539-1 Abstract ( 362 )   [Full Text(HTML)] () PDF (708KB) ( 1063 )   Ag-Cu-Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas-phase epoxidation of propylene by molecular oxy-gen and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and O2 temperature programmed desorption. Ag-Cu-Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibited the highest catalytic performance for gas-phase epoxidation of propylene by molecular oxygen. A propylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under the reaction conditions of 20% C3H6-10% O2-70% N2, 200℃, 0.1 MPa and 3000 h-1. Increasing the Cl loading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Ag crystallite size. The appropriate Cl loading of Ag-Cu-Cl/BaCO3 catalyst can reduce the dissociation adsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, which benefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag-Cu-Cl/BaCO3 catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Cl poisoning. The appropriate Cu loading of Ag-Cu-Cl/BaCO3 catalyst is efficient for the epoxidation of propylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivity because the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, which was shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag-Cu-Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.

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Fabrication and catalytic behavior of hierarchically-structured nylon 6 nanofiber membrane decorated with silver nanoparticles Huihui Zhao, Weimin Kang, Xiaomin Ma, Nanping Deng, Zongjie Li, Bowen Cheng 2017, 38 (1):  73-82.  DOI: 10.1016/S1872-2067(16)62545-7 Abstract ( 428 )   [Full Text(HTML)] () PDF (1632KB) ( 928 )   A hierarchically-structured nylon 6 (PA6) nanofiber membrane decorated with silver nanoparticles (Ag NPs) was fabricated by electrospinning and impregnation methods. The as-fabricated hierar-chically-structured Ag/PA6 nanofiber membrane (HS-Ag/PA6 NM) exhibits a morphology in which Ag NPs are deposited on the surfaces of both thick fibers and thin fibers. The content and size of the Ag NPs can be controlled by varying the concentration of the silver colloid solution. Compared with the non-hierarchically-structured Ag/PA6 nanofiber membrane, HS-Ag/PA6 NM has a higher spe-cific surface area and exhibits a higher degradation rate for methylene blue of 81.8%-98.1% within 2 h. HS-Ag/PA6 NM can be easily recycled and exhibits good reusability. It retains a degradation rate for methylene blue of 83.5% after five consecutive cycles. The hierarchically-structured nano-fiber membrane is therefore a potential nanocatalyst.

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Ag-loaded mesoporous Pb3Nb2O8 photocatalysts with enhanced activity under visible-light irradiation Xiaopeng Han, Jianan Lü, Li Tian, Lingru Kong, Xuemei Lu, Yong Mei, Jiwei Wang, Xiaoxing Fan 2017, 38 (1):  83-91.  DOI: 10.1016/S1872-2067(16)62575-5 Abstract ( 348 )   [Full Text(HTML)] () PDF (1005KB) ( 838 )   Mesoporous Pb3Nb2O8 photocatalysts were synthesized by the evaporation-induced self-assembly (EISA) method. Ag was deposited on the surface of mesoporous Pb3Nb2O8 by a facile photoreduction process. The as-prepared samples were characterized by TG-DSC, XRD, N2 adsorption, HR-TEM and UV-Vis spectroscopy. The results revealed that mesoporous Pb3Nb2O8 has a large specific surface area and uniform pore size distribution both before and after Ag deposition. The photodegradation of 2-propanol and acetaldehyde gas under visible-light (λ>420 nm) irradiation was employed to evaluate the photocatalytic activities of the samples. The results showed that the photocatalytic activity of mesoporous Pb3Nb2O8 is greatly improved by the Ag co-catalyst. These mesoporous Pb3Nb2O8 exhibit photocatalytic activities as much as 41 times higher when compared with the Pb3Nb2O8 prepared by the solid state reaction method. The content of loaded Ag ranged from 0.5% to 5% (Ag2SO4). The optimal loading was determined to be 1% corresponding the highest photo-catalytic activity. These results clearly indicate that the activity of Pb3Nb2O8 can be improved to obtain an outstanding performance for the photodegradation of organic pollutants.

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Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion Peng Xu, Zhixing Wu, Jiguang Deng, Yuxi Liu, Shaohua Xie, Guangsheng Guo, Hongxing Dai 2017, 38 (1):  92-105.  DOI: 10.1016/S1872-2067(16)62567-6 Abstract ( 431 )   [Full Text(HTML)] () PDF (1406KB) ( 1243 )   Ordered mesoporous Mn2O3 (meso-Mn2O3) and meso-Mn2O3-supported Pd, Pt, and Pd-Pt alloy x(PdyPt)/meso-Mn2O3; x=(0.10-1.50) wt%; Pd/Pt molar ratio (y)=4.9-5.1 nanocatalysts were prepared using KIT-6-templated and poly(vinyl alcohol)-protected reduction methods, respectively. The meso-Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble-metal nanoparticles (NPs) of size 2.1-2.8 nm were uniformly dispersed on the meso-Mn2O3 surfaces. Al-loying Pd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso-Mn2O3 gave the best performance; T10%, T50%, and T90% (the temperatures required for achieving methane conversions of 10%, 50%, and 90%) were 265, 345, and 425℃, respectively, at a space velocity of 20000 mL/(g·h). The effects of SO2, CO2, H2O, and NO on methane combustion over 1.41(Pd5.1Pt)/meso-Mn2O3 were also examined. We conclude that the good catalytic performance of 1.41(Pd5.1Pt)/meso-Mn2O3 is associated with its high-quality porous structure, high adsorbed oxy-gen species concentration, good low-temperature reducibility, and strong interactions between Pd-Pt alloy NPs and the meso-Mn2O3 support.

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Thermodynamic study of direct amination of isobutylene to tert-butylamine Shangyao Gao, Xiangxue Zhu, Xiujie Li, Yuzhong Wang, Ye Zhang, Sujuan Xie, Jie An, Fucun Chen, Shenglin Liu, Longya Xu 2017, 38 (1):  106-114.  DOI: 10.1016/S1872-2067(16)62550-0 Abstract ( 532 )   [Full Text(HTML)] () PDF (601KB) ( 1206 )   On basis of thermodynamic empirical equations, the thermodynamic parameters for the direct amination of isobutylene to tert-butylamine, an atomically economic and green chemical reaction, were calculated. In particular, the equilibrium conversion of isobutylene under various reaction conditions close to those used in industry was calculated and discussed. Isobutylene amination is a temperature sensitive reaction due to its exothermic nature and isobutylene equilibrium conver-sion decreases with temperature. However, kinetically, the amination reaction will be faster at a higher temperature. Thus, there must be an optimum temperature for the reaction. A high pressure and n(NH3)/n(i-C4H8) molar ratio promote the transformation of isobutylene to tert-butylamine. Developing a highly efficient catalyst under mild reaction conditions is preferred for the amination process. The reaction was investigated over a series of acidic zeolites. ZSM-11 zeolite exhibited the best performance with 14.2% isobutylene conversion (52.2% of the equilibrium conversion) and > 99.0% tert-butylamine selectivity. The effect of reaction conditions on the performance of the ZSM-11 catalyst agreed with the thermodynamic results, which provides guidance for further cata-lyst development and reaction condition optimization.

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Cu(I)-catalyzed cascade reaction of N-tosylhydrazones with 3-butyn-1-ol: A new synthesis of tetrahydrofurans Mohammad Lokman Hossain, Kang Wang, Fei Ye, Yan Zhang, Jianbo Wang 2017, 38 (1):  115-122.  DOI: 10.1016/S1872-2067(16)62565-2 Abstract ( 712 )   [Full Text(HTML)] () PDF (704KB) ( 1053 )   The Cu(I)-catalyzed cascade coupling/cyclization reaction of N-tosylhydrazones with 3-butyn-1-ol has been explored. This new strategy represents a simple platform for the synthesis of tetrahydro-furans in moderate to good yields.

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Enhanced MTO performance over acid treated hierarchical SAPO-34 Shu Ren, Guojuan Liu, Xian Wu, Xinqing Chen, Minghong Wu, Gaofeng Zeng, Ziyu Liu, Yuhan Sun 2017, 38 (1):  123-130.  DOI: 10.1016/S1872-2067(16)62557-3 Abstract ( 424 )   [Full Text(HTML)] () PDF (584KB) ( 1296 )   Hierarchical SAPO-34 crystals were synthesized by a facile acid etching post-treatment. Butter-fly-shaped porous patterns on four side faces and hierarchical pores composed of micropores, mesopores and macropores were formed after a nitric acid or oxalic acid treatment. The catalytic performance of the hierarchical SAPO-34 for the methanol to olefins (MTO) process showed that the synergistic effect of the hierarchical pores and acid sites resulted in a longer catalyst lifetime (from 210 to 390 min for the acid treated SAPO-34) and higher selectivity to light olefins of 92%-94%. The ethylene selectivity can be adjusted between 37.4% and 51.5% by the pore size. No hierarchical SAPO-34 was obtained after a treatment with butanedioic acid, and with this sample, fast deactiva-tion was detected after 100 min.

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Preparation of graphene/MgCl2-supported Ti-based Ziegler-Natta catalysts by the coagglomeration method and their application in ethylene polymerization Hexin Zhang, Jae-Hyeong Park, Young-Kwon Moon, Eun-Bin Ko, Dong-ho Lee, Yanming Hu, Xuequan Zhang, Keun-Byoung Yoon 2017, 38 (1):  131-137.  DOI: 10.1016/S1872-2067(16)62559-7 Abstract ( 351 )   [Full Text(HTML)] () PDF (1858KB) ( 1245 )   We report a facile coagglomeration method for preparing graphene (G)/MgCl2-supported Ti-based Ziegler-Natta catalysts. The effects of graphene feed ratio on catalyst morphology and ethylene polymerization behavior were examined. The synthesized catalyst exhibited very high activity for ethylene polymerization. The resultant polyethylene (PE)/G nanocomposites showed a layered morphology, and the graphene fillers were well dispersed in the PE matrix. In addition, the thermal stability and mechanical properties of PE were significantly enhanced with the introduction of a very small amount of G fillers (0.05 wt%). This work provides a facile approach to the production of high-performance PE.

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Enhancing hydrothermal stability of nano-sized HZSM-5 zeolite by phosphorus modification for olefin catalytic cracking of full-range FCC gasoline Yun Zhao, Jiaxu Liu, Guang Xiong, Hongchen Guo 2017, 38 (1):  138-145.  DOI: 10.1016/S1872-2067(16)62579-2 Abstract ( 316 )   [Full Text(HTML)] () PDF (513KB) ( 1164 )   In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano-sized HZSM-5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800℃ for 4 h (100% steam) and employed as catalysts for olefin catalytic cracking (OCC) of full-range fluid catalytic cracking (FCC) gasoline. X-ray diffraction, N2 physical adsorption and NH3 temperature-programmed desorption analysis indicated that, although signifi-cant improvements to the hydrothermal stability of nano-sized HZSM-5 zeolites can be observed when adopting both phosphorus modification strategies, impregnation with trimethyl phosphate displays further enhancement of the hydrothermal stability. This is because higher structural crys-tallinity is retained, larger specific surface areas/micropore volumes form, and there are greater numbers of surface acid sites. Reaction experiments conducted using a fixed-bed micro-reactor (catalyst/oil ratio=4, time on stream=4 s) showed OCC of full-range FCC gasoline-under a fluid-ized-bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gaso-line. This reaction significantly decreased the olefin content in the full-range FCC gasoline feed, and specifically heavy-end olefins, by converting the olefins into value-added C2-C4 olefins and aromat-ics. At the same time, sulfide content of the gasoline decreased via a non-hydrodesulfurization pro-cess. Nano-sized HZSM-5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full-range FCC gasoline.

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Influence of preparation methods on the physicochemical properties and catalytic performance of MnOx-CeO2 catalysts for NH3-SCR at low temperature Xiaojiang Yao, Kaili Ma, Weixin Zou, Shenggui He, Jibin An, Fumo Yang, Lin Dong 2017, 38 (1):  146-159.  DOI: 10.1016/S1872-2067(16)62572-X Abstract ( 651 )   [Full Text(HTML)] () PDF (830KB) ( 1119 )   This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx-CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3-SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation, hydrothermal treatment, co-precipitation, and a sol-gel technique, were used to synthesize MnOx-CeO2 catalysts. The catalysts were characterized in detail, and an NH3-SCR model reaction was chosen to evaluate the catalytic performance. The results showed that the preparation methods affected the catalytic performance in the order:hydrothermal treatment > sol-gel > co-precipitation > impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content, oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sites and acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalyst formed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal cata-lytic performance, and good H2O resistance in NH3-SCR reaction. This was attributed to incorpora-tion of Mnn+ into the CeO2 lattice to form a uniform ceria-based solid solution (containing Mn-O-Ce structures). Strengthening of the electronic interactions between MnOx and CeO2, driven by the high-temperature and high-pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environ-ment-friendly route to synthesizing low-temperature denitrification (deNOx) catalysts.

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Influence of sulfation on CeO2-ZrO2 catalysts for NO reduction with NH3 He Zhang, Yonggang Zou, Yue Peng 2017, 38 (1):  160-167.  DOI: 10.1016/S1872-2067(16)62581-0 Abstract ( 505 )   [Full Text(HTML)] () PDF (559KB) ( 981 )   CeO2-ZrO2 (CeZr) and sulfated CeO2-ZrO2 (S-CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (<200℃) and lower activity at high temperatures (> 200℃) than the S-CeZr catalysts. The sulfation of CeZr was studied in terms of surface acidity, redox properties and NO adsorption-desorption by temperature-dependent experiments and in situ infrared spectroscopy. S-CeZr displayed high con-centrations of acidic sites and increased surface acidities, but poor reducibility compared with CeZr. The high acidity of S-CeZr was attributed to the presence of Brønsted acid sites, arising mainly from the surface sulfates. Because the surface was covered with sulfate species, S-CeZr showed lower NO adsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Brønsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle oc-curred easily at relatively low temperatures (150℃), and the weakly bound nitrite was partially activated on the S-CeZr catalyst at relatively high temperatures (300℃). The catalytic mechanisms for the CeZr and S-CeZr catalysts at 150 and 300℃ were also studied.

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A shaped binderless ZSM-11 zeolite catalyst for direct amination of isobutene to tert-butylamine Wanshuo Zhang, Shangyao Gao, Sujuan Xie, Hui Liu, Xiangxue Zhu, Yongchen Shang, Shenglin Liu, Longya Xu, Ye Zhang 2017, 38 (1):  168-175.  DOI: 10.1016/S1872-2067(17)62756-6 Abstract ( 576 )   [Full Text(HTML)] () PDF (906KB) ( 1389 )   A shaped binderless and two binder-containing ZSM-11 zeolite catalysts were prepared and char-acterized by powder X-ray diffraction, N2 adsorption-desorption, and pyridine adsorption-infrared measurements. The binderless catalyst was synthesized using a dry-gel conversion technique, in which 1,6-hexanediamine and tetrabutylammonium bromide were used as structure-directing agents and no other alkaline materials were added. The catalytic performance of the zeolites in the direct amination of isobutene to tert-butylamine was evaluated in a fixed-bed reactor. By virtue of its high crystallinity as well as its good mechanical strength, the shaped binderless ZSM-11 catalyst showed a higher rate of formation of tert-butylamine than did the binder-containing catalysts.