天然气化学 Natural Gas Chemistry

Size: px

Start display at page:

Download "天然气化学 Natural Gas Chemistry"

Louisa Randall
5 years ago
Views:

1 June 18, 2007, DICP 天然气化学 Natural Gas Chemistry 潘秀莲催化基础国家重点实验室,

2 Outlines 1. General introduction to energy map 2. General about Natural Gas 3. Conversion and utilization of Natural Gas 3.1 Direct Conversion 3.2 Indirect conversion via syngas

3 简单历史 19 世纪前, 以木材粮食农副产品为基本原料的化工 ; 19 世纪末, 煤化工 : 焦化干馏气化等 ; 20 世纪初, 煤化工进一步发展 ; 20 世纪 50 年代, 石油的年消耗量增大, 炼油石油加工业 ; 20 世纪末, 化工 80% 以上的基础原料来自石油化工 ; 20 世纪 80 年代, 石油资源日趋枯竭,OPEC 禁运措施, 价格猛涨, 以及环境影响, 研究和开发替代石油的新能源 ;

4 Energy use grows with economic development

5 Current and historical global energy mix 26.5% 6.1% 6.1% 37.3% 50% 45% 40% 35% 30% 23.9% 25% 20% Oil Coal Hydro Natural Gas Nuclear 15% 10% 5% 预计 2025 年天然气的比重将高于 40%, 超过石油的能源结构中的比重 0% Source: BP Statistical Review

Five key drivers of the energy future significant hydrocarbon resource potential misalignment between resource location and demand growing supply challenges growth of renewables rapid GDP growth esp.

6 Five key drivers of the energy future significant hydrocarbon resource potential misalignment between resource location and demand growing supply challenges growth of renewables rapid GDP growth esp. in developing countries growth of megacities changing customer preferences Demand Growth Supply & Resources Security of Supply Technology Environmental Constraints advances in all technologies especially info-tech, biotech and nanotech potential for breakthroughs in energy production, conversion or storage significant rise in import dependence new policy initiatives to enhance energy security growing competition for energy resources climate change and potential for carbon constraints regulation relating to local pollution Source: BP Statistical Review

7 Renewed interest in N Gas: Environmental restriction and Relatively clean N Gas More domestic gas than once thought Energy imbalance and security Expanded uses

8 Outlines 1. General introduction to energy map 2. General about natural gas 3. Conversion and utilization of natural gas

9 What is NG? Colorless, shapeless, and odorless in its pure form, a mixture of hydrocarbon gases. Typical Composition of Natural Gas Methane Ethane CH 4 C 2 H % Propane C 3 H % Butane Carbon Dioxide Oxygen Nitrogen Hydrogen sulphide Rare gases C 4 H 10 CO 2 O 2 N 2 H 2 S A, He, Ne, Xe 0-8% 0-0.2% 0-5% 0-5% trace

11 Usa of Natural Gas 1. Clean fuel commercial and residential use; 2. Raw material for chemical industry (ammonia synthesis, methanol, ethylene, propene, hydrogen, syngas, acetylene, carbon black...) Note: 76%ammonia, 80% methanol, 42% ethylene comes from Natural Gas.

12 The supply and demand of NG in China Natural Gas,10 8 m supply demand Year

13 NGas Utilization in China Domestic (10 8 M 3 ) Natural Gas Coal-based Import (10 8 M 3 ) pipe line LNG Total

14 NGas Resource Distribution in China

15 Size Distribution of Gas Fields in China > M 3 14 (44.3%) 100~ M 3 50~ M 3 < M 3 30 (27.9%) 27 (12.9%) 138 (14.8%) 204 Gas Fields in Total

16 Pipeline Project in China 12x 10 9 M 3 /y

17 Outlines of this lecture 1. General introduction to energy map 2. General about Natural Gas 3. Conversion and utilization of Natural Gas What and how? Why important?

18 天然气转化和利用的核心是催化优化能源结构保护生态缓解石油供应不足

19 催化对社会进步的贡献 Fe N 2 + 3H 3 O 4 -Al 2 O 3 -K 2 O 2 2NH 3 合成氨熔铁催化剂使化肥工业迅速发展迎来了现代农业 1918 年诺贝尔化学奖乙烯丙烯 TiCl 3 -AlR 3 Cp 2 Ti(Ph) 2 聚乙烯聚丙烯 Ziegler-Natta 催化剂塑料产量增加了 100 倍奠定了石化工业的基础 1963 年诺贝尔化学奖

20 国际天然气利用研究情势 Re-injection LNG CH 4 Gas Sales Power Generation Syngas (CO, H2) Acetic Acid Hydrogen Fischer-Tropsch Products Ammonia Methanol Refineries Fuel Edib.Oil/Fat Clean Fuels Lubricants Wax Alpha Olefins Urea Acrylonitrile Fertilisers DME, Formaldehyde Solvents, MTBE Clean Fuels, Fuel Cells Power Generation Olefins

21 Research in Industrial Companies Syngas Manufacture GTL, Methanol in the Joint Research Center with CAS Syngas and GTL in a CNPS Laboratory in the Petroleum University Daqing Beijing Lanzhou Xi an Syngas, Methanol and GTL in Southwest Institute for Natural Gas BP-CAS Program Clean Energy Facing Future Natural Gas, Hydrogen Shanghai Sichuan Low Alkanes Conversion, Hong Kong in SINOPC Institute

22 Research in Academia Methane Coupling in Lanzhou Institute of Chem. Phys. Syngas from Coal, methanol, GTL in Taiyuan Institute of Coal Chem. Syngas, H2, Oxygenates, olefins, GTL, Aromatics Fundamental Research at DICP Beijing Taiyuan Lanzhou Xi an Nanjing Sichuan Syngas and Catalytic Combustion in Sichuan Uni. Syngas, Acetylene and Methanol at Institute of Organic Chem. Xiamen Dalian H2 and C1 Chemistry in Tianjing Uni. Shanghai Low Alkane Conversion, Fundamental Research in Nanjing Uni. Hong KongFundamental Research on Methane Activation In Xiaman Uni.

23 National Major Basic Research Program (MOST, 973) 天然气煤层气优化利用的催化基础 99 年 10 月 2004 年 9 月 ; 设计 2 个大学,3 个研究所, 共 32 位教授和 35 位研究人员 ; 总体目标 : 发展一系列以催化为核心的科学和技术转化为高洁净度液体燃料和具更高经济价值且便于运输的甲醇烯烃芳烃和含氧化物等基本化工原料基础研究 : 以 C-H 选择活化和定向转化为目标, 创新催化过程和催化剂, 建立和发展动态催化理论, 从本质上认识控制活化选择转化的核心问题

24 National Major Basic Research Program (MOST, 973) 天然气及合成气高效催化转化的基础研究 2005 年 1 月 2009 年 12 月 ; 涉及 8 个大学,2 个研究所,60 多位研究人员 ; 子课题 : 天然气制合成气及规模制氢和 CO 2 处理 ; 合成气制取高品质液体燃料 ; 合成气制含氧化物 ; 基于合成气和天然气的高温燃料电池 ; 天然气直接催化转化 ; 天然气高效转化的非常规过程 ; 催化剂和催化体系的构效关系和动态表征 ; 催化过程的微观机制和反应中间体的鉴定

25 Features of CH 4 C-H 键能 : 438.8kJ mol -1 电离势 : 12.5eV 质子亲和势 : 4.4eV 酸性 (pka): 48 自然界中最稳定的有机分子之一最具挑战性和机遇

26 Property of CH 4 Molecular weight Volume (standard)(l/mol) Density (101.32kPa, 0 C)(kg/m3) Boiling point/k Thermal conductivity (101.32kPa, 0 C)(W/m.K) Explosion limit in air (20 C)% Autogenous ignition T/K Combustion heat/(kj/m3)

27 一些简单反应的标准自由能变化 Reaction ΔG Ө / (kcal/mol) 400 K 1000 K 2 CH 4 C 2 H H CH 4 C 2 H 6 + H CH 4 + O 2 C 2 H H 2 O CH 4 + ½ O 2 C 2 H 6 + H 2 O CH 4 + Cl 2 CH 3 Cl + HCl CH 4 + ½ O 2 CH 3 OH CH 4 + CO CH 3 CHO CH 4 + CO 2 CH 3 COOH CH 4 + H 2 O CO + H CH 4 + CO + ½ O 2 CH 3 COOH 甲烷的转化和利用, 化学工业出版社,2005

28 甲烷的催化转化 C-H 键的活化是催化循环的一部分, 而不是计量反应 ; 催化体系有足够的选择性, 即产物中 C-H 键比甲烷稳定 ; 体系的活性应该足够高使反应在温和条件下进行

29 Conversion of methane Selective Oxidation Direct Conversion Oxidative coupling (OCM) Decomposition to H2 + C Aromatization Natural gas (CH 4 ) Catalytic Combustion NH 3 syn Electricity Syngas (CO+H 2 ) Methanol Ethylene, etc DME Liquid fuels: F-T syn. Oxygenates

30 Direct Conv Selective Oxidation 气相均相氧化气固多相催化氧化反应条件 4 MPa, C, 影响因素很多反应条件 C, 多采用 SiO 2 或 Al 2 O 3 负载的 MoO 3, V 2 O 5 等催化剂 ; 甲醇产率 <5% 注 : 问题难以控制选择性氧化从工业化角度, 转化率 >10%, 选择性 >80% 液相催化氧化常以过渡金属配合物为催化剂, 以强酸超强酸超临界流体为溶剂, 以 O 2 H 2 O 2 K 2 S 2 O 8 SO 3 为氧化剂

31 Difficulty of direct methanol synthesis: C-H bonding of CH kj/mol CH 3 OH kj/mol Some transition metal complexes could selectively activate the more stable C-H bond? Oxidative addition; σ bond displacement; free radical; electrophilic activation. Advantage of low T synth: Protection of product in acid medium (ester) Direct Conv

32 Examples for low T Direct Conv G. Olah Electrophiles and superacids, Periana et al. Science, 1993, 340; Science 1998, 560. Net reaction: CH 4 + 1/2O 2 Con. CH4 50%, yield 43% HgSO 4 /H 2 SO CH 3 OH

33 More examples Direct Conv Fujiwara et al. Angew. Chem. Int. Ed. 2000, 2475 CaCl 2, Pd (OAc) 2 /Cu(OAc) 2 CF 3 CO 2 H/(CF 3 CO 2 ) 2 O CH 4 + CO CH 3 COOH K 2 S 2 O 8, 85 ºC 20 atm CH4; 0.5 mmol CaCl2, 15 h reaction time, 1.05 mmol product. Bell et al. JACS 2003, 125, 4406 CH 4 + SO 2 + K 2 S 2 O 8 CF 3 SO 3 H, CaCl 2 65 C CH 3 SO 3 H 69 atm CH 4 ; triflic acid; 10 h, 1.44 mmol product.

34 Work of Sen et al.? Direct Conv H 2 O 2 + CH 4 (CF 3 CO) 2 O PdCl2, 90 C CF 3 COOCH 3 0 CF CH 4 Pd H + 3 COOH + + CF 3 COOCH Pd C CF 3 COOH + CH 3 OH? Stoichiometric E. Gretz, et al. J. Am. Chem. Soc. 109 (1987) 8109; L. Kao, et al. J Am Chem Soc 113 (1991) 700

35 Pd 0 Pd 2+? Direct Conv Wacker process: CuCl 2 /CuCl/O 2 Others?

36 The Wacker Process Direct Conv Developed simultaneously by Wacker-Chemie and by the group of Moiseev. It involves the reaction of ethylene with PdCl 2 in HCl (reaction 1). Pd(II) is reduced to Pd black. To make the reaction catalytic, Pd(0) is reoxidized by CuCl 2 and O 2 (reactions 2 and 3). 2- C 2 H 4 + Pd Cl + 3H 2 O CH 3 CHO+Pd 0 +2H 3 O+4Cl - 4 (1) Pd 0 +2CuCl 2 +2Cl - 2- Pd Cl 4 + 2CuCl (2) CuCl+ 4H 3 O + + 4Cl - + O 4CuCl 2 + 6H 2 O (3) 2

37 Direct Conv Better to explore To make a catalytic process; To avoid HCl, H 2 SO 4, SO 3, SO 2 ; To use O 2 as oxidant.

38 Combination of Pd 2+ and Q Run Pd 2+ Q O 2 CF 3 COOCH 3 Pd2+a (μmol) (μmol) (atm) (μmol) (%) Conditions: CF 3 COOH: 3 ml (39 mmol), CH 4 : 54 atm (114 mmol), O 2 : 1 atm (2 mmol), 80 ºC, 10 h; a: Remaining Pd 2+ after the reaction. OH 2+ O CF + Pd + 2 H + + Pd 0 3 COOH CH 4 + CF 3 COOCH 3 O OH O + 1/2O 2 + H 2 O OH + Pd0 + 2H + + Pd 2+ O OH

39 Scheme of methane oxidation O H CH + CF COOH 4 3 Pd 2+ 1/2O 2 OH O CF 3 COOCH 3 Pd 0 + 2H + O

40 Search for active oxidants to speed up: Direct Conv OH OH O + 1/2O 2 + H 2 O O nitrogen oxide /CH 2 Cl 2 Bosch, et al. J. Org. Chem. 1994, 59, Feasibility test in CF 3 COOH OH O + NO 2 + NO + H 2 O OH O

41 Combination of Pd 2+ & Q: Direct Conv Run Pd 2+ Q NaNO 2 O 2 CF 3 COOCH 3 Pd2+a (μmol) (μmol) (μmol) (atm) (μmol) (%) CF 3 COOH: 3 ml (39 mmol), CH 4 : 54 atm (114 mmol), O 2 : 1 atm (2 mmol), 80 ºC, 10 h; a: Remaining Pd 2+ after the reaction.

42 CF 3 COOCH 3 (umol) reaction time (h) A catalytic process Q and NaNO2 key to prevent the precipitation of Pd Pd key, determining the TON The yield to CF 3 COOCH 3 versus the reaction time. TON: 0.7 h -1

43 Further confirmation Direct Conv Run Pd 2+ Q NaNO 2 O 2 CF 3 COOCH 3 Pd2+a (μmol) (μmol) (μmol) (atm) (μmol) (%) isotope experiments GC-MS O 2 14 atm 13 CH 4 -COO 13 CH 3 (m/e = 60) 40 atm 12 CH 4 CF 3 COOH -COO 12 CH 3 (m/e = 59) 1 3

44 Direct Conv Low T selective oxidation of CH 4 OH CH 4 + CF 3 COOH Pd 2+ NO 2 OH CF 3 COOCH 3 Pd 0 + 2H + O H 2 O + NO 1/2O 2 O CH 4 + 1/2O 2 CH 3 OH Catalytic process in one pot at 80 C O 2 as oxidant TON = 0.7 h -1 An, Pan, Bao et al. JACS 128 (2006)

45 直接法制甲醇的状况 Direct Conv 直接法的优点 : 反应放热, 从能耗上有利 ; 工艺和设备简单工业化的要求 : 单程转化率 10 ~ 15%, 选择性 80 ~ 90% 目前水平 : 转化率 2 ~ 4%, 选择性 40 ~ 70%

46 Direct Conv High Temperature Conversion of Methane to Aromatics

47 Direct Conv Typical HT Direct Conversion Process Selective Oxidation CH 4 + O 2 CH 3 OH+CO 2 +H 2 O Oxidative Coupling CH 4 + O 2 C 2 H x +CO 2 +H 2 O

48 A New Route Direct Conv To higher hydrocarbons, without forming CO 2? CH 4 + O 2 6CH 4 Mo/HZSM-5 Higher HC C 6 H 6 + 9H 2 Y. Xu,, et al.,catal. Lett.. 21 (1993) 35-41

49 Conversion of methane to aromatics Direct Conv H CH 3 C M H CH 3 C M nch 3 n/2c 2 H x Catalysts Mo, W, Re HZSM-5, MCM-22

50 Bifunctionality of Mo/HZSM-5 Acidity and catalytically active sites

51 Aromatization over different Mo species 30 Mo species related to B acid sites(moc x O y ) Mo species in the form of Mo 2 C Mo species supported on SiO 2 n Highly active and stable MoC x O y ; TOF 20 n Low activity and stability of Mo 2 C; 10 n 0.5 acidic sites per unit cell required for 0 30min 240min 600min aromatization. D. Ma, X. Bao et al., Chem. Eur. J. 8 (2002), Y. Xu, X. Bao, et al., J. Catal (2003).

52 Effect of pore morphology MCM-22 ZRP-1 Percentage (%) ZSM-5 ZSM-11 JQX-1 SBA-15 Conv.of CH 4 Sel.of BTX Sel.of Nap. Sel.of coke ESR ring 0.4nm 10ring 0.55nm 10\12 12ring 0.75nm meso >1nm Applied Catalysis A-general A 188 (1-2) 2),J. Catal (2003)

53 Comparison between Mo/ZSM-5 and Mo/MCM-22 Open Mo/HMCM-22 Solid Mo/HZSM-5 Y. Shu,, X. Bao et al., Catal. Lett.. 70 (2000) 67.

54 Pore morphology of carriers Shape selectivity size (dynamic( diameter of benzene (0.59 nm) crossing with two-dimensional structure micro-mesoporous mesoporous composite

55 Achievements over the years Direct Conv Convers before < 10% 18% (Coupled) Yield 10 to Benzene ~6-8% ~12% Life time 6 6~8 h ~50 h 4 yield C, 1atm with a flow rate of 1500mL/gcat. h

56 Conversion of methane Indirect Conv Selective Oxidation Direct Conversion Oxidative coupling (OCM) Decomposition to H2 + C Aromatization Natural gas (CH 4 ) Catalytic Combustion NH 3 syn Electricity Syngas (CO+H 2 ) Methanol Ethylene, etc DME Liquid fuels: F-T syn. Oxygenates

57 Methane to syngas Direct Conv CH 4 + ½ O 2 CO + 2 H 2 CH 4 + H 2 O CO + 3 H 2 CH 4 + CO 2 2CO + 2 H 2 ΔH 298K = kj/mol ΔH 298K = kj/mol ΔH 298K = 247 kj/mol 一般采用镍催化剂, 反应温度 700 C 以上, 通过调节改变原料气比例和反应可以调节合成气的组成

58 Syngas to ammonia NH 3 synth 国际上合成氨的原料构成 / % 原料焦炭煤焦炉气天然气石脑油重油其他合计

59 我国合成氨的原料构成 / % NH 3 synth 原料焦炭煤焦炉气天然气石脑油重油其他合计

60 NH 3 synth o C o C N 2 Equilibrium Conversion (%) V N2 : V H2 = 1:3 200 o C 300 o C o C Reaction Pressure (atm) 热力学平衡转化率

61 NH 3 synth Fe (111) is 430 times more active than Fe (110) and Fe (100) is 30 times higher. Al 2 O 3 and K 2 O are additives. A 首先在表面生成与 Fe 同晶的 FeA , 然后以这种新的表面为模板, 使 α -Fe 晶体生长向 (111) 或 (211) 面定向暴露在反应混合物中

62 Recent progress in NH 3 synthesis NH 3 synth N 2 在不同物质上的吸附热及其与氨合成活性的关系 Norskov, JACS 2001 Co 3 Mo 3 N, Ru, Fe 催化剂的氨合成活性 Ba is a significantly better promoter for metals at the right-hand side of the volcano curve than for metals at the left side, whereas the opposite is true for the alkali metal promoters. JC 2003.

63 NH 3 synth Effect of catalyst supports K/Ru/C = 2/10/100, atmospheric pressure, N 2 /3H 2 30 ml/min, GHSV 637 h -1. Activity of K-promoted Ru catalysts supported on: SiO 2 < zeolite (NaX) < AC<γ-Al 2 O 3 < CeO 2 < C < MWNT Liao DW, Appl. Surf. Sci

64 Syngas to methanol methanol Methanol (CH 3 OH) is an alcohol fuel. lower emissions, higher performance, and lower risk of flammability than gasoline. Methanol is a fundamental raw material for chemicals. The third most demanded raw materials for organics following olefins and aromatics, to HCHO, CH3COOH, MTBE, 醋酸酐, 甲酸甲酯, 二甲醚, 乙二醇, 乙醛, 乙醇等

65 methanol Syngas to methanol 合成氨和甲醇是天然气化工中具有优势的大宗化学品领域, 工艺成熟, 但对新型高效催化剂和反应器的研究一直没有间断 CO + 2H 2 k 1 k -1 CH 3 OH 第一套装置 BASF 在 20 世纪 20 年代建立采用 ZnO-Cr2O3 为催化剂, 反应温度 C, 反应压力为 25-75MPa 1966 年英国 ICI 推出了低压合成甲醇, 采用高活性的 Cu 基催化剂, 压力 5-10MPa

66 MTO Syngas to olefin via methanol 石脑油合成气乙烯高分子材料化工原料

67 MTO Demand of Ethylene Year Ethylene demand/mton

分子筛催化性能随结构的变化 90 95 90 85 80 75 总烯收率 1998 2000 2003 Olefin

68 分子筛催化性能随结构的变化总烯收率 Olefin selectivity (wt%) C2= C3= 0 SAPO-44/A SAPO-44/B SAPO-44/C

69 ZSM-11 SAPO-34 SAPO-5 ZSM-22 Pulsed methanol reaction at 400 C, GC analysis results low 70% 80% 90%

70 F-T Fischer-Tropsch 过程制备液体燃料原油油品汽油柴油 H 2 O CH 4 O 2 部分氧化 CO H 2 费 - 托合成天然气合成气液体燃料

71 复杂的 F-T 反应 : F-T nco + (2n+1)H 2 C n H 2n+2 + nh 2 O nco + 2nH 2 C n H 2n + nh 2 O nco + 2nH 2 C n H 2n+2 O + (n-1) 1)H 2 O CO + H 2 O CO 2 + H 2 还有 : 水煤气变换醇脱水烯烃加氢异构化析炭反应等产物 : 低碳烃 (C 1 ~ C 4 ) 汽油 (C 5 ~ C 11 ) 柴油 (C 12 ~ C 18 ) 蜡 (C 19+ ) 及醇醛酸酯等

72 F-T 合成油的历史和主要国际公司 F-T 1925, Fischer & Tropsch 30 年代中压合成, 先后在德美法前苏联南非等建立合成油厂 ; 60 年代, 石油开采,F-T 失去活力 70 年代, 石油资源紧张,F-T 开发继续 Sasol( 南非 );Shell ( 荷兰 );Exxon( 美国 ); Syntroleum ( 美国 ); BP( 英国 ); Rentech ( 美国 ).

73 F-T 合成气制液体燃料钴基催化剂 -500 小时稳定性试验结果 : 甲烷选择性 <6% C + 5 选择性 >90% 链增长几率 >0.90 蜡油比在 3.8 左右形成低甲烷重质烃固定床工艺与 Shell 公司水平相当, 高于其他国际公司中科院山西煤化所

74 热力学 F-T CO + H 2 CH 4 + H 2 O ΔH 298K = - 206kJ/mol CO + 5H 2 C 2 H 6 + 2H 2 O ΔH298K = - 347kJ/mol 2CO + 2H 2 CH 3 COOH ΔH298K = - 215kJ/mol 2CO + 3H 2 CH 3 CHO + H 2 O ΔH298K = - 457kJ/mol 2CO + 4H 2 CH 3 CH 2 OH + H 2 O ΔH298K = - 256kJ/mol 强放热反应, 在 C 内, 产物生成的概率是 CH 4 > 饱和烃 > 烯烃 > 含氧化物实际产物分布与催化剂反应条件等相关

75 Anderson-Schulz-Flory 分布 F-T m n = (1-a)a n-1 m: 具有 n 个碳原子的烃类产物的 mol 分数 ; a: 碳链增长概率, 取决于催化剂和反应条件, 随温度升高而降低, 随 H 2 /CO ratio 而降 Ru-based cats Co-based cats Fe-based cats 0.85 ~ ~ ~ 0.70

76 F-T 过程中的产物控制 F-T CH 4 突破 Schulz-Flory 分布的限制柴油碳原子数 (n)

77 Product distribution F-T H 2 dissociative adsorption on most transition metal. Cu (molecular adsorption) methanol Ni (dissociative adsorption) CH 4 Co, Fe (strong bonding of Metal-C) C 2+

78 Reaction mechanisms under debate: F-T 碳化物机理含氧中间体机理 CO 插入机理双中间体机理 C2 活性物种理论烯烃重吸附理论涉及 : 链引发 ( 即反应开始时活泼的表面物种的形成 ) 链增长 ( 碳链的形成 ) 链终止 ( 最终产物的生成 )

79 碳化物机理 : F-T H H H 2 聚合 CO M-C C M 金属碳化物亚甲基 = -CH 2 -CH 2 -CH 2 - CO 插入机理 : H CO M H C = M O H H H C M O M -H 2 O 2H CH 2 = M CH 3 M CO CH 3 C M = O 烯烃重吸附机理 : 烯烃重新在催化剂表面吸附, 加氢生成烷烃异构化裂解反应插入反应等

80 Possibility of syngas to olefins? F-T Fe 基催化剂特点 : 常用的载体 :Al 2 O 3, SiO 2, zeolite, Activated carbon 助剂 :K, Cu, Mn 优点 : 低碳烯烃高选择性, 高辛烷值的汽油 ; 缺点 : 对水煤气变换高活性, 高温时易积炭, 链增长能力差其它 : 在反应中复杂的相组成变化注 : 燃烧的抗震程度以辛烷值表示, 辛烷值越高表示抗震能力愈高

81 Possibility of syngas to olefins? Progress Degussa, Fe-ZnO-K 2 O-V (or Mn, Ti) (100:10:4~8) H 2 /CO = 1/:1, 75% sel. C 2= ~C = 4 Shell, Fe-K-Cu-Zn/SiO 2 (25:5:10:20), mainly 58% C 5+ cracking in the following step DICP K-Fe-MnO/SiO 2, H 2 /CO = 2, 1000 h test stability

82 Use Carbon as support F-T Steen, catal.today 2002 Coville, appl.catal General finding: Lower CH 4 and higher olefin selectivity compared to other Fe/C cats. Reasons are not known yet.

83 碳材料家族 F-T sp 2 bonding carbon graphite sp 3 bonding carbon fullerene onion-like carbon (OLC) diamond carbon black, activated carbon,. Tokyoetc Shigeo MARUYAMA,, UnivU niv. Tokyo nanotube filaments

Geometrical confinement; Graphitic layers Thermal

84 Carbon Nanotubes F-T Multiwalled CNTs Higher purity compared to AC Well defined morphology of nanochannels Geometrical confinement; Graphitic layers Thermal stability, electron conductivity; Unique H 2 adsorption and activation capability.

85 More examples F-T Cat. Reaction Comments Ref. Rh/MWNT NO decomposition Higher conversion than with a Rh/Al2O3 Luo et al., Catal Lett 2000 Co/MWNT Cyclohexanol dehydrog. Act. & sel. to cyclohexanone Liu et al., Catal Lett 2001 Pt/CNT Cathod catalyst higher power density Sun et al, Carbon 2002 Co/MWNT F-T synthesis Steen et al, Catal Today 2002; Bezemer et al., JACS 2006 Rh/MWNT Cinnamaldehyde hydrog. Act. 3 times higher than Rh/C catalyst Giordano et al., Eur J Inorg Chem 2003 Pt/CNT Nitrobenzen hydro. High act. compared AC Li et al., J Mol Cat 2005

86 Why encapsulates? F-T Geometrical confinement Curvature causes binding energy: Interior > groove sites > external. [Yates, Chem Phys Lett 383 (2004) 314] Template for Beta-zeolite synthesis and CoFe 2 O 4 Nhut et al., Appl. Catal. 2003, 254, 345 Theoretical calculation: Reaction in CNT channels Santiso et al. Appl.Surf.Sci.2005, 252, 766

nanotubes; (b) Fe 2 O 3 nanoparticles dispersed on its

87 F-T Introduction of Fe 2 O 3 nanoparticles into carbon nanotube channels (a) Fe 2 O 3 nanoparticles inside nanotubes; (b) Fe 2 O 3 nanoparticles dispersed on its outer wall Chen, Pan, Bao et. al., JACS, 2006, 128, 3136.

88 Syngas directly to olefin F-T

89 物理化学性质的表征并与反应活性关联 F-T TEM, SEM 等形貌, 如粒子大小, 分散情况等 ; XRD, Mossobauer 谱,XPS 制备过程和反应前后催化剂组成晶相和价态的变化 ; TPR 等技术表面铁氧化物中在载体表面还原的难易程度, 金属 - 载体的相互作用, 吸附脱附行为等 ; FT-IR,Raman 表面活性物种 ; XAFS 晶体周围环境的信息, 如金属原子的配位数等

Fe 2 O 3 @CNTs encapsulates F-T TEM Images RT

90 Fe 2 O encapsulates F-T TEM Images RT 600 Chen, Pan, Bao et. al., JACS, 2006, 128, 3136.

Autoreduction of Fe 2 O 3 @CNTs with varying diameters F-T T Fe 2 O

91 Autoreduction of Fe 2 O with varying diameters F-T T Fe 2 O Fe@CNTs + CO Fe Chen, Pan, Bao JACS, article, 2007, 129, 7421

92 Fe 2 O encapsulates F-T Fe-O mode: Bulk Fe 2 O 3 at 283 cm -1

93 Fe 2 O encapsulates F-T Chen, Pan, Bao JACS, article, 2007, 129, 7421

94 Oxidation of encapsulates + O 2 Fe 2 O A Gas 1 Gas 2 Gas 3 Purge Gas Preheater 20 ºC MFC MFC MFC MFC B A: Fe-in-CNTs; Zone control 20 ºC 20 ºC Δ Δm= 2m f f o MS B: Fe-out-CNTs; C: Fe-in-SBA-15 GC 20 ºC Heater 2

95 Transformation monitored in situ by XRD Fe Fe 2 O 3 Chen, JACS, article, 2007, 129, 7421

96 Stabilization of metallic Fe inside carbon nanotube channels.

97 Corelation between the structure and catalytic activity & selectivity?

98 C2 oxygenates synthesis (mainly ethanol) C2-Oxy Fermentation Syngas ethanol Fuel, fuel additive Raw material for chemical industry Natural gas Coal Biomass Rh-based catalyst. Catalytic process is a beneficial supplementary.

99 Scheme of oxygenate synthesis from syngas C2-Oxy

100 Beyond the effect of particle size C2-Oxy RhMn-in-CNT RhMn-out-CNT C 2 oxygenates yield as a function of time on stream Pam, Fan, Chen, Bao et al, Nature Materials 2007, 6, 507

101 The effect of particle size C2-Oxy RhMn-out-CNTs RhMn-in-CNTs Catalyst fresh Post-reaction/120 h RhMn-out-CNTs 2-4 nm 5-8 nm RhMn-in-CNTs 1-2 nm 4-5 nm

102 Syngas to higher alcohols alcohols Definition: a mixture of alcohols of C 1 ~ C 6. Usage: Cats in research: Clean transportation fuel or fuel additives, high octane number; raw material of chemicals. Modified F-T cats (Cu-Co, Mo-based); Modified methanol cats (Cu-Zn, Zn-Crbased). Difficulties: Low activity, selectivity, stability, and economically unfavorable

103 CNT-promoted methanol cats alcohols CNTs+Cu-ZnO-Al 2 O 3 in the syngas conversion to methanol CuZnOAl 2 O %CNTs-CuZnOAl 2 O 3 CO conversion 29.5% 42.4% MeOH formation rate /μmol MeOH s -1 (m 2 surf Cu) K, 2.0MPa, feed gas H 2 /CO/CO 2 /N 2 = 62/30/5/3(v/v), GHSV = 3000 h -1 The promotion effect : (1) an excellent dispersant of catalyst components; (2) an excellent adsorbent, activator and reservoir of H 2. HB Zhang s group, Chem. Commun., 2005, 5094; Catal. Lett. 85, 2003, 237

104 CNT-promoted cats alcohols Co 3 Cu 1-11%CNTs Co 3 Cu 1 At 50 bar, H 2 /CO/CO 2 /N 2 = 46/46/5/3, GHSV 10 4 ml h -1 gcat -1. TPR indicated a lowered reduction temperature, increasing the Co x Cu y species reducible to lower valence-state.

105 alcohols (a)co 3 Cu 1 and (b) Co 3 Cu 1-11%CNT fed with CO 2 containing syngas; (c)co 3 Cu 1 and (d) Co 3 Cu 1-11%CNT fed with CO 2 free syngas. H 2 -TPD (a) Co 3 Cu 1-11%CNT; (b) Co 3 Cu 1 Indicate: (1) presence of surface Co n+ species (CoOOH/Co 3 O 4 ) may be closely related to the highly selective formation of HAS. (2) Presence of reversible active H species.

106 主要科学问题选择氧化过程中的氧物种及选择性控制合成气转化中的产物分布的控制调节, 尤其 CH 4 形成机理和抑制甲烷的高效直接转化, 包括酶催化转化以甲醇为原料的新化学过程贵金属替代的可能性

107 主要科学问题催化过程的原位动态表征高温稳定催化剂的控制合成基于纳米概念的催化理论

108 部分阅读文献 : 1. G.A. Somorjai, Chemistry in Two Dimensions: Surfaces. Cornell University Perss, Ithaca, NY 1981 和中译本 2. G.A. Somorjai, Introduction to Surface Chemistry and Catalysis, John Wiley & Sons, Inc A. Sen, Catalytic functionalization of carbon-hydrogen and carboncarbon bonds in protic media, Acc. Chem. Res. 31 (1998) R.H. Crabtree, Aspects of Methane Chemistry, Chem. Rev. 95 (1995) Z. Liu et al., New Progress in R & D of lower olefin synthesis, Fuel Processing Technology 62 (2000) H. Dai, Carbon Nanotubes: Synthesis, Integration, and Properties, Accounts Chemical Research 35 (2002) R.A. Sheldon, Chemicals from synthesis gas, D. Reidel Publishing Company, 贺黎明, 沈召军, 甲烷的转化和利用, 化学工业出版社, 汪寿建等, 天然气综合利用技术, 化学工业出版社, 周怀阳等, 天然气水合物, 海洋出版社,2000.

Direct Catalytic Conversion of Methane

Direct Catalytic Conversion of Methane Xiulian Pan, Zengjian An, Ding Ma, Yide Xu, Xinhe Bao State Key Laboratory of Catlaysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences www.fruit.dicp.ac.cn