Applied Catalysis B: Environmental 179 (2015) 95\u2013105 Contents lists available at ScienceDirect Applied Catalysis B: Environmental j ourna l h om epage: www.elsev ier .com/ locate /apcatb In\ufb02uence of the surface oxygenated groups of act prepar rog the oxi Guoqian o J Key Laboratory of Co Technology, Ta a r t i c l Article history: Received 27 N Received in re Accepted 1 Ma Available online 7 May 2015 Keywords: Cu/AC catalyst Surface oxygenated groups Dispersion Valence distrib Deactivation treat e carb chara tion, CO adsorption, and TPR. The results show that the concentrations of nitric acid do not signi\ufb01cantly changes the speci\ufb01c surface area and textural property of AC. But the oxygenated groups which result in acidic properties, such as lactone, carboxyl and phenol groups, are formed on AC surface during the acid treatment process and increase with the increasing concentration of nitric acid. The increased surface oxygenated groups not only in\ufb02uence the dispersion but also the valence distributions of copper species. 1. Introdu Support hydrogenat and ethano sis reaction [4,5]), oxida to CO2 ) to N2 , n (such as m carbonate [1 SiO2 and ze large surfac mentioned \u2217 Correspon Tel.: +86 351 6 E-mail add http://dx.doi.o 0926-3373/© utions When copper supported on the AC treated by 4 M HNO3, the Cu/AC catalyst shows the optimal catalytic performance for oxidative carbonylation of methanol to dimethyl carbonate, which might be ascribed to the highest dispersion of Cu+ and Cu0 species. The average conversion of methanol and space-time yield of DMC (STYDMC) within 10 h for the catalyst have reached 9.2% and 229 mg g\u22121 h\u22121, respectively. The deactivation of Cu/AC catalysts is attributed to the agglomeration of copper species. Besides, the STYDMC of per S(Cu+ + Cu0) for the acid treated Cu/AC catalysts is very similar and less than that of the original Cu/AC catalyst which may be induced by the AC surface oxygenated groups itself but not the ratio of Cu+/Cu0. © 2015 Elsevier B.V. All rights reserved. ction ed Cu-based catalysts have been widely investigated in ion reaction (such as hydrogenation of CO to methanol l [1,2], dimethyl oxalate to glycol ), hydrogenoly- (such as hydrogenolysis of glycerol to 1,2-propanediol tion reaction (such as oxidation of SO2 to SO3 , CO , reduction reaction (such as reduction of nitric oxide itrate to N2 ) and oxidative carbonylation reaction ethanol to dimethyl carbonate and ethanol to diethyl 0,11]). Many materials including AC, Al2O3, CeO2, ZrO2, olite [8,12\u201319] are employed as supports to provide a e area for copper species dispersion. Among the above catalyst supports, AC exhibits the favorable physical ding author at: No. 79 Yingze West street, Taiyuan 030024, China. 018526; fax: +86 351 6018526. ress: firstname.lastname@example.org (Z. Li). and chemical characteristics for the preparation of a catalyst with the \ufb01ne dispersion of an active copper species on the AC support [19\u201321]. This fact has drawn researchers\u2019 attention and consider- able efforts have been made to investigate the performances and characteristics of these supported Cu/AC catalysts. It is known that the catalytic activity of supported catalyst is strongly dependent on the dispersion of active species over the sup- port . In order to obtain the \ufb01ne dispersion of copper species over AC support, various techniques such as impregnation tech- nique , liquid phase reduction , and chemical precipitation  have been used to fabricate Cu/AC catalyst. For example, Lu et al.  found the size of Cu particles was about 100\u2013150 nm of the Cu/AC catalysts prepared by polyol reduction. Wang et al.  employed chemical precipitation to prepare Cu/AC catalysts and showed the crystalline size of Cu was about 42.6 nm. Besides, previous studies have shown that the surface oxygenated groups enhance the hydrophilicity of the AC allowing easy access of metal salt solutions during the impregnation process and provide addi- tional nucleation sites, which could further improve the dispersion rg/10.1016/j.apcatb.2015.05.001 2015 Elsevier B.V. All rights reserved. ation of a nano Cu/AC catalyst and hete dative carbonylation of methanol g Zhang, Zhong Li \u2217, Huayan Zheng, Tingjun Fu, Yub of Coal Science and Technology of Ministry of Education and Shanxi Province, Institute iyuan 030024, Shanxi, China e i n f o ovember 2014 vised form 28 April 2015 y 2015 a b s t r a c t Coconut shell activated carbon (AC) is heterogeneous catalysts for oxidativ and their corresponding catalysts are ivated carbon on eneous catalysis in u, Yuchun Wang al Chemical Engineering, Taiyuan University of ed by nitric acid and used as a support to prepare nano-copper onylation of methanol to dimethyl carbonate. AC supports cterized intensively by BET, XPS, XRD, TEM, N2O chemisorp- 96 G. Zhang et al. / Applied Catalysis B: Environmental 179 (2015) 95\u2013105 of active species [26,27]. Generally, AC pretreatment by HNO3 is believed to be an available way for the formation of more sur- face oxygenated groups onto AC . Zhu et al.  reported that AC treated by HNO3 had more active surface complexes such as carboxyls a decreased f alyst disper of N2O and produced m persion of C increased fr the amoun dispersion h In additi also plays a previous st for NO redu of CuO and the presenc improveme the synthes the AC supp were repor reported th among the the catalytic Generally, t copper pre valence dis tion temper AC [24,30,3 temperatur formation o pare Cu/AC moderate t The availab support, es the precurs distribution reduction s more Cu2O on AC treat AC. Even so genated gro the support In this p surface che catalysts. Th texture stru in\ufb02uence o and phenol catalyst has of Cu/AC ca are evaluat 2. Experim 2.1. Prepara A comm 1643 m2/g try Co. Ltd. of HNO3 (fr tilled water overnight. The pretreated AC is denoted as AC-x, where x represents the concentration of HNO3. The catalysts with 11.2 wt.% Cu loadings are prepared by an incipient wetness impregnation method. An aqueous solution of 3)2 i r 6 h. d in x. arac text ed b C us as o orpt ore v ed at ples re pa face Boeh ic sit was dium bic aken was Cl. T .1 M use l va ns b alcul ylic, ylic ylic g ay ph ALab diat ess an dhes into eva ple The ined ced ay di D/M 5406 s of atmo nsmi ith ed by pano evap ted b was f the of ea lume zed w pera ed nd lactones, and the grain size of the supported Cu2O rom 16.5 nm to 12.4 nm which led to the improved cat- sion as well as the catalytic activity for the reduction NO. Rau et al.  also found that HNO3 treatment ore active surface complexes which improved the dis- uO over AC support, and the removal ef\ufb01ciency of SO2 om 56.4% to 84.2%. Be that as it may, the in\ufb02uence of t of surface oxygenated groups on the copper species as not been thoroughly researched so far. on, the valence of copper species over the AC support n important role in catalytic performance. According to udies , the high catalytic activity of Cu/AC catalyst ction in the presence of oxygen was owing to existence Cu2O species. But when NO reduction was conducted in e of NH3, Cu2O and metallic Cu was detrimental for the nt of catalytic performance of CuO/AC catalysts . In is of DMC by oxidative carbonylation of methanol, all orted copper catalysts (Cu0/AC, Cu2O/AC and CuO/AC) ted to show good catalytic activity [18,32]. Li et al.