不同载体负载Pd双功能催化剂制备及其液相甲醇催化一步合成甲酸甲酯
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摘要
以γ-Al_2O_3、ZrO_2、Bentonite(膨润土)、MIL-53(Al)和MIL-53(Fe)为载体,采用浸渍法制备负载Pd双功能催化剂,利用XRD、BET和NH3-TPD等表征催化剂结构,在微型高压反应器中评价催化剂的液相甲醇一步催化转化合成甲酸甲酯的反应性能,考察反应条件对催化剂性能的影响。结果表明,不同载体负载Pd催化剂未观察到Pd的XRD特征峰,表明催化剂表面的Pd是高分散状态。不同载体负载Pd催化剂的比表面积、酸强度和酸量差别较大,并且酸强度和酸量对甲醇转化率和产物选择性有较大影响。具有较多中强酸的2%Pd/Bentonite、2%Pd/MIL-53(Al)和2%Pd/MIL-53(Fe)催化剂比中强酸较少的2%Pd/γ-Al_2O_3和2%Pd/ZrO_2催化剂具有更高的甲醇转化率和甲酸甲酯选择性。2%Pd/Bentonite催化剂在每摩尔甲醇Pd用量为0. 030 mmol、反应温度150℃、O_2压力2 MPa和反应时间5 h条件下,液相甲醇一步催化转化合成甲酸甲酯反应中,甲醇转化率56. 08%,甲酸甲酯选择性55. 85%。
Pd-loaded bifunctional catalysts with γ-Al_2O_3,ZrO_2,bentonite,MIL-53( Al) and MIL-53( Fe)as supports were prepared by impregnation method and characterized by XRD,BET and NH_3-TPD techniques. Catalytic performance of the catalyst in one-step conversion of liquid phase methanol to methyl formate and the effect of reaction conditions on performance of the catalyst were evaluated in a micro-high-pressure reactor. The results showed that characteristic peaks of Pd were not observed in all XRD patterns of the catalysts,which might be due to high dispersion state of Pd on catalyst surface. Catalysts with different supports had large differences in specific surface area,acid strength and acid amount. Acid strength and acid amount of catalysts had a great influence on methanol conversion and product selectivity.2% Pd/Bentonite,2% Pd/MIL-53( Al) and 2% Pd/MIL-53( Fe) catalysts with more medium and strong acid sites had higher methanol conversion and methyl formate selectivity than 2% Pd/γ-Al_2O_3 and 2% Pd/ZrO_2 catalysts with less strong acid sites. Conversion of methanol was 56. 08% and selectivity of methyl formate was 55. 85% over 2% Pd/Bentonite catalyst under the conditions of amount of palladium per mole of methanol was 0. 030 mmol,reaction temperature was 150 ℃,reaction pressure was 2 MPa,and reaction time was 5 h.
Pd-loaded bifunctional catalysts with γ-Al_2O_3,ZrO_2,bentonite,MIL-53( Al) and MIL-53( Fe)as supports were prepared by impregnation method and characterized by XRD,BET and NH_3-TPD techniques. Catalytic performance of the catalyst in one-step conversion of liquid phase methanol to methyl formate and the effect of reaction conditions on performance of the catalyst were evaluated in a micro-high-pressure reactor. The results showed that characteristic peaks of Pd were not observed in all XRD patterns of the catalysts,which might be due to high dispersion state of Pd on catalyst surface. Catalysts with different supports had large differences in specific surface area,acid strength and acid amount. Acid strength and acid amount of catalysts had a great influence on methanol conversion and product selectivity.2% Pd/Bentonite,2% Pd/MIL-53( Al) and 2% Pd/MIL-53( Fe) catalysts with more medium and strong acid sites had higher methanol conversion and methyl formate selectivity than 2% Pd/γ-Al_2O_3 and 2% Pd/ZrO_2 catalysts with less strong acid sites. Conversion of methanol was 56. 08% and selectivity of methyl formate was 55. 85% over 2% Pd/Bentonite catalyst under the conditions of amount of palladium per mole of methanol was 0. 030 mmol,reaction temperature was 150 ℃,reaction pressure was 2 MPa,and reaction time was 5 h.
引文
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[24]Wojcieszak R,Karelovic A,Gaigneaux E M,et al. Oxidation of methanol to methyl formate over supported Pd nanoparticles:insights into the reaction mechanism at low temperat ure[J]. CatalysisScience&Technology,2014,4(9):3298-3305.
[25]Chen X F,Zang H,Wang X,et al. Metal-organic framework MIL-53(Al)as a solid-phase microextraction adsorbent for the determination of 16 polycyclic aromatic hydrocarbons in water samples by gas chromatography-tandem mass spectrometry[J]. Analyst,2012,137(22):5411.
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[2]李静,苏栋根.我国甲醇市场的现状与未来发展[J].石油化工技术与经济,2013,29(4):12-16.Li Jing,Su Donggen. Current status and future development of Chinese methanol market[J]. Techno-Economics in Petrochemicals,2013,29(4):12-16.
[3]杨晓娟,段继锋.甲醇及下游产业发展前景分析[J].化工管理,2016,(18):21.
[4]Koivikko N,Laitinen T,Ojala S. Formaldehyde production from methanol and methylmercaptan over titania and vanadia based catalysts[J]. Applied Catalysis B:Environmental,2011,103(1):72-78.
[5]Anthony Goodrow,Alexis T Bell. A theoretical investigation of the selective oxidation of methanol to formaldehyde on isola-ted vanadate species supported on silica[J]. Journal of Physical Chemistry C,2007,111(40):14753-14761.
[6]Karanjit S,Bobuatong K,Fukuda R,et al. Mechanism of the aerobic oxidation of methanol to formic acid on Au-8:a DFT study[J]. International Journal of Quantum Chemistry,2013,113(4):428-436.
[7]Hansen J A,Ehara M,Piecuch P. Aerobic oxidation of methanol to formic acid on Au-8:benchmark analysis based on completely renormalized coupled-cluster and density functional theory calculations[J]. Journal of Physical Chemistry A,2013,117(40):10416-10427.
[8]Solyman S M,Betiha M A. The performance of chemically and physically modified local kaolinite in methanol dehydration to dimethyl ether[J]. Egyptian Journal of Petroleum,2014,23(3):247-254.
[9]Catizzone E,Aloise A,Migliori M,et al. Dimethyl ether synthesis via methanol dehydration:effect of zeolite structure[J]. Applied Catalysis A:General,2015,502:215-220.
[10]Nikonova O A,Capron M,Fang G,et al. Novel approach to rhenium oxide catalysts for selective oxidation of methanol to DMM[J]. Journal of Catalysis,2011,279(2):310-318.
[11]Wang Tuo,Meng Yali,Zeng Liang,et al. Selective oxidation of methanol to dimethoxymethane over V2O5/Ti O2-Al2O3catalysts[J]. Science Bulletin,2015,60(11):1009-1018.
[12]Phillips K R,Jensen S C,Baron M,et al. Sequential photooxidation of methanol to methyl formate on Ti O2(110)[J].Journal of the American Chemical Society,2013,135(2):574-577.
[13]Lang X,Wen B,Zhou C,et al. First-principles study of methanol oxidation into methyl formate on rutile Ti O2(110)[J]. Journal of Physical Chemistry C,2014,118(34):19859-19868.
[14]Wang Ruiyi,WuZhiwei,ChenChengmeng,etal. Graphenesupported Au-Pd bimetallic nanoparticles with excellent catalytic performance in selective oxidation of methanol to methyl formate[J]. Chemical Communications,2013,49(74):8250-8252.
[15]师瑞萍,王辉,朱华青,等.不同温度焙烧的Au-Pd/Si O2催化剂上甲醇选择性氧化制备甲酸甲酯[J].燃料化学学报,2012,40(8):985-991.Shi Ruiping,Wang Hui,Zhu Huaqing,et al. Methanol selective oxidation to methyl formate on Au-Pd/Si O2catalysts with different calcination temperatures[J]. Journal of Fuel Chemistry&Technology,2012,40(8):985-991.
[16]Han Chenhui,Yang Xuzhuang,Gao Guanjun,et al. Selective oxidation of methanol to methyl formate on catalysts of AuAg alloy nanoparticles supported on titania under UV irradiation[J]. Green Chemistry,2014,16(7):3603-3615.
[17]Wang H,An K,Sapi A,et al. Effects of nanoparticle size and metal/support interactions in Pt-catalyzed methanol oxidation reactions in gas and liquid phases[J]. Catalysis Letters,2014,144(11):1930-1938.
[18]Yang Xuzhuang,Zhang Aiwen Gao Guanjun,et al. Photocatalytic oxidation of methanol to methyl formate in liquid phase over supported silver catalysts[J]. Catalysis Communications,2014,43(2):192-196.
[19]Shi Da,Liu Jianfang,Sun Rui,et al. Preparation of Bifunctional Au-Pd/Ti O2,catalysts and research on methanol liquid phase one-step oxidation to methyl formate[J].Catalysis Today,2018,316:206-213.
[20]Siddique M,Ilyas M,Saeed M. Synthesis,characterization and catalytic activity of Pd supported zirconia for the oxidation of benzyl alcohol in liquid phase solvent free conditions[J]. Journal of the Chemical Society of Pakistan,2016,38(3):454-462.
[21]Wang Xueming,Wu Guangjun,Guan Naijia,et al. Supported Pd catalysts for solvent-free benzyl alcohol selective oxidation:effects of calcination pretreatments and reconstruction of Pd sites[J]. Applied Catalysis B:Environmental,2012,s115-116(5):7-15.
[22]Whiting G T,Kondrat S A,Hammond C,et al. Methyl for mate formation from methanol oxidation using supported goldpalladiumnanoparticles[J]. AcsCatalysis,2015,5(2):637-644.
[23]Wojcieszak R,Ghazzal M N,Gaigneaux E M,et al. Low temperature oxidation of methanol to methyl formate over Pd nanoparticles supported onγ-Fe2O3[J]. Catalysis Science&Technology,2014,4(3):738-745.
[24]Wojcieszak R,Karelovic A,Gaigneaux E M,et al. Oxidation of methanol to methyl formate over supported Pd nanoparticles:insights into the reaction mechanism at low temperat ure[J]. CatalysisScience&Technology,2014,4(9):3298-3305.
[25]Chen X F,Zang H,Wang X,et al. Metal-organic framework MIL-53(Al)as a solid-phase microextraction adsorbent for the determination of 16 polycyclic aromatic hydrocarbons in water samples by gas chromatography-tandem mass spectrometry[J]. Analyst,2012,137(22):5411.
[26]Dong Wenfei,Yang Liaoyuan,Huang Yuming. Glycine postsynthetic modification of MIL-53(Fe)metal-organic framework with enhanced and stable peroxidase-like activity for sensitive glucose biosensing[J]. Talanta,2017,167:359-366.