Preparation and activity of ni mgo al2o3 catalysts in the partial oxidation of methane

PREPARATION AND ACTIVITY OF Ni-MgO/α-Al2O3 CATALYSTS IN THE PARTIAL OXIDATION OF METHANE A Thesis Presented to The Faculty of Graduate School College of Engineering De La Salle University In Partial Fulfillment of the Requirements for the Degree in Master of Science in Chemical Engineering by Doan, Long The Nam August 9, 2005 PREPARATION AND ACTIVITY OF Ni-MgO/α-Al2O3 CATALYSTS IN THE PARTIAL OXIDATION OF METHANE A Thesis Presented to The Faculty of Graduate School College of Engineering De La Salle University In Partial Fulfillment of the Requirements for the Degree in Master of Science in Chemical Engineering by Doan, Long The Nam August 9, 2005 ACKNOWLEDGEMENT It is very glad for me to express my deepest appreciation to everyone who gave me his or her valuable support which help me finished my thesis on time Special thanks to my advisors, Dr Luis Razon, Dr Carlito Salazar, Professor Hiroo Niiyama and Dr Leonila Abella for their guidance, support and contribution Without them, this thesis would not have been done Gratitude and appreciation are for the following persons and institutions who have contributed to the accomplishment of my work JICA/AUN/SEED-Net for financial support and great consideration Ho Chi Minh City University of Technology, Vietnam; De La Salle University, The Philippines and Tokyo Institute of Technology, Japan Professor Hirofumi Hinode, Professor Takashi Aida, Dr Susan Gallardo, Dr Servillano Olaño for giving their precious advice Ms Gladys Cruz for consideration in my work and my life in the Philippines Mr Benjie Cardoza, Mr Manny Burgos and Mr Peter Ascrate for technical advice and lending equipment Engr Neil Macadaeg, Mr Sojo Akelardo, Mr Ismael Serrano for lending equipment All of my Philippine and Vietnamese friends for their encouragement To my family and my country, my success is always dedicated to you ABSTRACT Partial Oxidation is considered to be a promising method to convert natural gas to synthesis gas (“syngas”) Because the reactions involved are difficult to control, it is necessary to investigate appropriate catalysts for this process in order to maximize CH4 conversion and the yield of CO and H2 The catalyst should have high activity and high selectivity as well as high stability At the same time, it should be available at low cost Effect of catalyst preparation methods (all slight variants of the precipitation method), Ni/Mg molar ratio and reaction temperature on the performance of Ni/MgO catalysts supported on α-Al2O3 in the partial oxidation of methane to syngas has been investigated A fixed bed flow system was used to conduct the reaction The ratio of CH4: O2: N2: He equals to 12: 6: 14: 68 was used in the study Three catalyst preparation methods produced comparable results in CH4 conversion, CO and H2 Energy Dispersive X-Ray (EDX) analysis and the color of the catalysts after reaction showed that one method was superior due to its higher carbon deposition resistance Ni/Mg molar ratio affected the reduction temperatures and the performance of the catalysts significantly When the ratio decreased, activity decreased and reduction temperature increased The catalyst that has Ni/Mg molar ratio of 1/2 was chosen since it gave the same results as the catalyst that has Ni/Mg molar ratio of in similar conditions At a Ni/Mg molar ratio of 1/2 and reduction temperature of 8500C, CH4 conversion and CO selectivity increased (about 65-98% and 65-96%, respectively) when reaction temperature was increased from 600 to 8000C while H2 selectivity remained almost the same (about 90%) This may be the first time when Ni-MgO/α-Al2O3 catalysts prepared by precipitation method were investigated The catalyst gave excellent activity and remained stable after h time-on-stream TABLE OF CONTENTS Chapter Introduction 1.1 Background of the study 1.2 Statement of the problem 1.3 Objectives of the Study 1.3.1 General Objective 1.3.2 Specific Objectives 1.4 Significance of the Study 1.5 Scope and limitations of the Study Chapter Review of Related Literature 2.1 Synthesis Gas Production and Catalytic Partial Oxidation 2.2 Partial oxidation Catalysis 2.2.1 Active Components 2.2.2 Catalyst Supports 2.2.3 Promoters 11 2.2.4 Reduction 12 2.2.5 Thermal processes and Sintering 13 2.2.6 Carbon Deposition on Ni-based Catalysts 14 2.2.7 Catalyst Preparation Methods 16 2.3 The development of catalysts contain Ni-MgO-Al2O3 17 2.4 Catalytic Partial Oxidation Mechanism 18 2.5 Heat transfer consideration 23 2.6 Reaction Temperature and Other Operating Conditions 24 Chapter Theoretical Considerations 3.1 Catalytic Partial Oxidation of Methane 26 3.2 Partial Oxidation Catalysis 28 3.2.1 Active Component 28 3.2.2 Active Sites 28 3.2.3 Catalyst Support 29 3.2.4 Catalyst Promoters 31 3.2.5 Catalyst Deactivation 33 3.2.6 Thermal processes and Sintering 34 3.2.7 Carbon Deposition 35 3.2.8 Precipitation Method 36 3.3 Catalyst Characterization 38 3.3.1 Scanning Electron Microscopy (SEM) method 38 3.3.2 Energy Dispersive X-ray (EDX) method 38 3.4 Product Gas Analysis Chapter 39 Methodology 4.1 Catalyst Preparation 4.1.1 Catalyst Preparation Methods 42 42 a) Method 42 b) Method 43 c) Method 44 4.1.2 Catalyst Preparation Calculation 4.2 Equipment 45 46 4.2.1 Experimental Set up 46 4.2.2 Gas Chromatography Unit 49 4.2.3 Scanning Electron Microscopy and 50 Energy Dispersive X-ray unit 4.3 Experiment Design 4.3.1 Calibration of equipment a) Flowmeters 51 52 52 b) Gas Chromatography Unit 53 4.3.2 Leak Test 53 4.3.3 Blank test 53 4.3.4 Experiment procedure 54 4.3.5 Effect of catalyst preparation procedures 55 4.3.6 Effect of Ni/Mg molar ratio 55 4.3.7 Effect of reaction temperature 55 4.4 Products Analysis using Gas Chromatography Chapter 56 Results and Discussion 5.1 Blank tests 58 5.2 Effect of Catalyst Preparation Methods 58 5.2.1 Time-on-stream test 58 5.2.2 Catalyst color consideration and EDX results 62 5.3 Effect of Ni/Mg molar ratio 64 5.3.1 Time-on-stream test 64 5.3.2 EDX results 67 5.4 Effect of temperature 69 5.4.1 Time-on-stream test 69 5.4.2 EDX results 74 Chapter Conclusion and Recommendation 6.1 Conclusion 76 6.2 Recommendation 77 References 79 Appendix A Catalyst Calculation 88 Appendix B Flowmeter Calibration 89 Appendix C Gas Chromatography Calibration 94 Appendix D Catalyst Surface Analysis by SEM and EDX 106 Appendix E Experiment Results 115 LIST OF FIGURES Figure 2-1: Suggested reaction scheme for partial oxidation of methane 19 Figure 2-2: Surface and gas phase temperature profiles measured 23 respectively with IR thermography with thermocouples Figure 3-1: Thermodynamic equilibrium line of partial oxidation of 27 methane Figure 3-2: Phases of nickel compounds present after calcination of 37 nickel alumina catalysts Figure 3-3: Schematic diagram of the filament bridge arrangement 41 in a typical TCD Figure 4-1: Reactor located in heater 48 Figure 4-2: Schematic diagram of experimental set-up 49 Figure 4-3: Gas Chromatogram 50 Figure 5-1: CH4 conversion as a function of time on stream at different 59 catalyst preparation methods for CPOM Figure 5-2: CO selectivity as a function of time on stream at different 60 catalyst preparation methods for CPOM Figure 5-3: H2 selectivity as a function of time on stream at different 61 catalyst preparation methods for CPOM Figure 5-4: Method 1’s fresh and used catalysts 62 Table E-13: Product gas analysis and calculation of trial of catalyst with Ni/Mg molar ratio =1/3 Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 14.3892 0.0000 14.6565 1.2934 3.9540 7.2626 68.5255 84.8834 83.5744 100.0000 0.5 11.7939 0.0000 15.0027 1.6064 4.0092 5.9566 68.8227 78.7601 66.6305 100.0000 1.0 10.8250 0.0457 15.0130 1.5262 4.2050 5.6424 67.3227 78.7105 62.4764 99.2898 1.5 11.3323 0.0107 15.0899 1.3949 4.4555 5.9550 65.5522 81.0220 66.8286 99.8350 2.0 11.3080 0.0185 14.9454 1.2835 4.5567 6.0115 64.4298 82.4057 68.5025 99.7110 2.5 11.5174 0.0085 14.9186 1.2124 4.6734 6.0979 63.4527 83.4146 70.9728 99.8675 3.0 11.3646 0.0227 14.8859 1.2904 4.6082 6.0580 63.8835 82.4398 69.7118 99.6435 3.5 11.7854 0.0205 14.7285 1.2761 4.7473 6.2542 62.3958 83.0540 74.8079 99.6758 4.0 11.7839 0.0133 14.5614 1.2256 4.7740 6.2469 61.7504 83.5986 76.4473 99.7876 4.5 11.4069 0.0142 14.6500 1.3047 4.6036 6.0598 63.3386 82.2834 71.7096 99.7742 5.0 11.6396 0.0140 14.6487 1.2710 4.6849 6.1707 62.6880 82.9207 73.9385 99.7769 134 4.4.2 Effect of reaction temperature For investigating effect of reaction temperature, the following conditions were used: - Catalyst preparation procedure: procedure - Reduction temperature: 8500C - Reaction temperature: 600, 650, 700, 750, 8000C - Ni/Mg molar ratio = 1/2 Two trials were done for each catalyst preparation method The result of catalyst performance at 7000C can be seen in Table E-10, E-11 and Fig E-9, E-10 Figure E-13: Chromatogram for of trial of catalyst with reaction temperature of 6000C (residence time: 4.5 h) 135 Figure E-14: Chromatogram for of trial of catalyst with reaction temperature of 6000C (residence time: 4.5 h) Figure E-15: Chromatogram for of trial of catalyst with reaction temperature of 6500C (residence time: 4.5 h) 136 Figure E-16: Chromatogram for of trial of catalyst with reaction temperature of 6500C (residence time: 4.5 h) Figure E-17: Chromatogram for of trial of catalyst with reaction temperature of 7500C (residence time: 4.5 h) 137 Figure E-18: Chromatogram for of trial of catalyst with reaction temperature of 7500C (residence time: 4.5 h) Figure E-19: Chromatogram for of trial of catalyst with reaction temperature of 8000C (residence time: 4.5 h) 138 Figure E-20: Chromatogram for of trial of catalyst with reaction temperature of 8000C (residence time: 4.5 h) 139 Table E-14: Product gas analysis and calculation of trial of catalyst with reaction temperature of 6000C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 13.3629 14.3423 2.6442 5.3308 4.7272 56.6369 64.1289 95.9620 100 0.5 13.1968 14.3750 2.9360 5.1157 4.6165 58.4813 61.1255 91.5716 100 1.0 13.1803 13.9366 2.7056 5.0628 4.7549 57.6181 63.7343 95.7473 100 1.5 12.7975 14.5224 2.7934 4.7038 4.4834 62.2117 61.6122 82.6288 100 2.0 12.9010 14.1806 2.9256 5.0405 4.5138 58.5308 60.6742 90.6695 100 2.5 12.8848 13.9383 2.8691 5.2151 4.5991 56.3485 61.5824 95.6980 100 3.0 12.7479 14.3745 2.7991 5.1067 4.5107 58.5529 61.7076 88.3516 100 3.5 12.8795 14.4454 2.7949 5.2052 4.5664 57.9608 62.0325 89.7330 100 4.0 12.7374 14.4338 2.7425 5.1965 4.5464 57.9973 62.3743 88.7583 100 4.5 12.9410 14.4065 2.8999 5.1721 4.5726 58.1153 61.1924 90.1645 100 5.0 12.8344 14.0952 2.8815 5.1368 4.4866 57.4825 60.8922 92.4029 100 140 Table E-15: Product gas analysis and calculation of trial of catalyst with reaction temperature of 6000C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 13.6980 13.3115 2.1426 3.8199 4.8809 66.5211 69.4938 90.2377 100 0.5 13.6176 13.4532 2.0000 4.2703 4.8979 62.9678 71.0057 93.7720 100 1.0 13.7417 13.5458 2.2189 3.6834 4.8899 68.2758 68.7866 86.6734 100 1.5 13.0549 13.8716 2.1222 4.6342 5.1308 61.0242 70.7404 89.9625 100 2.0 13.5859 13.2483 2.2440 4.3183 4.8042 61.9724 68.1621 96.5266 100 2.5 13.2624 13.0549 2.3683 3.6894 5.0479 67.0292 68.0659 88.4099 100 3.0 12.8830 13.2610 2.4950 4.2375 4.8866 62.7196 66.1997 90.3554 100 3.5 13.1370 13.6689 2.4342 4.4098 4.9456 62.3615 67.0154 89.9006 100 4.0 13.8951 13.7898 2.4018 4.3720 4.8710 63.2916 66.9756 93.2829 100 4.5 13.2937 14.3874 2.2048 4.5404 5.2117 63.1821 70.2717 85.3073 100 5.0 13.0572 14.2449 2.1745 4.7407 5.1022 61.1734 70.1169 87.4068 100 141 Table E-16: Product gas analysis and calculation of trial of catalyst with reaction temperature of 6500C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 16.0375 13.6753 1.5080 3.3293 7.3831 71.5971 83.0392 95.5479 100 0.5 17.3411 13.8545 1.5183 3.0155 7.1519 74.6069 82.4883 97.8641 100 1.0 16.0724 13.4395 1.4763 3.2127 7.1798 72.1109 82.9450 96.7416 100 1.5 16.0325 13.7504 1.4341 3.0025 6.9112 74.5250 82.8155 91.2643 100 2.0 16.0616 13.5145 1.5335 2.9225 6.9151 74.7709 81.8491 92.7199 100 2.5 15.9173 13.9137 1.5678 2.7398 6.8327 77.0267 81.3368 86.6368 100 3.0 16.0750 13.8532 1.5371 2.9642 6.9641 75.0366 81.9190 90.2079 100 3.5 15.9037 13.4254 1.4513 3.0043 6.9181 73.8926 82.6594 93.5161 100 4.0 15.9495 14.0120 1.5862 3.1756 6.9273 73.5593 81.3684 90.2664 100 4.5 16.0296 13.8789 1.6248 3.1363 6.8762 73.6361 80.8870 91.4942 100 5.0 15.8445 13.7479 1.6343 3.0256 6.8585 74.3243 80.7566 90.4541 100 142 Table E-17: Product gas analysis and calculation of trial of catalyst with reaction temperature of 6500C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 16.3028 13.6170 1.5221 2.9518 7.3492 74.7098 82.8424 93.4803 100 0.5 15.4673 14.6313 1.6916 4.0524 7.0196 67.6871 80.5813 91.1051 100 1.0 15.4420 14.7110 1.5016 3.6747 7.1670 70.8575 82.6777 86.4156 100 1.5 15.8730 13.6348 1.3839 3.0406 7.4876 73.9830 84.4006 91.7899 100 2.0 16.1329 14.0683 1.3512 3.1779 7.6823 73.6461 85.0424 90.8318 100 2.5 15.0079 14.0037 1.4262 3.2716 7.1013 72.7439 83.2753 85.9404 100 3.0 15.3316 13.8875 1.4151 3.0112 7.3280 74.7034 83.8147 86.2065 100 3.5 15.5166 13.7045 1.3198 3.2456 7.3654 72.3706 84.8040 91.2616 100 4.0 15.5586 13.7890 1.3739 3.1372 7.3124 73.4566 84.1831 89.6032 100 4.5 15.4899 13.3161 1.3600 2.6393 7.4322 76.8762 84.5317 88.2666 100 5.0 15.7467 13.8032 1.3740 3.4435 7.4969 70.8950 84.5112 93.8665 100 143 Table E-18: Product gas analysis and calculation of trial of catalyst with reaction temperature of 7500C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 19.6078 13.0440 0.3578 0.6449 9.6347 94.2320 96.4193 93.0543 100 0.5 19.3783 13.1037 0.4297 0.4946 9.4975 95.5964 95.6715 90.2396 100 1.0 19.4732 12.9095 0.3571 0.7929 9.6348 92.8343 96.4261 94.7842 100 1.5 19.1745 13.3716 0.3615 0.6433 9.5197 94.3872 96.3415 88.6225 100 2.0 18.6760 13.4086 0.4167 0.4515 9.2667 96.0716 95.6968 84.5712 100 2.5 19.3393 13.0811 0.3407 0.8240 9.6801 92.6510 96.6001 93.0815 100 3.0 19.2368 13.0845 0.3637 0.7793 9.6593 93.0514 96.3713 92.1657 100 3.5 19.1835 13.1036 0.5232 0.4080 9.5373 96.3674 94.7995 88.6184 100 4.0 19.4830 12.9217 0.4307 0.5895 9.7664 94.6776 95.7763 92.8979 100 4.5 19.1722 13.1692 0.4652 0.5342 9.6451 95.2675 95.3988 89.1425 100 5.0 19.3560 13.2745 0.4640 0.4875 9.6103 95.7155 95.3942 88.8653 100 144 Table E-19: Product gas analysis and calculation of trial of catalyst with reaction temperature of 7500C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 19.8730 13.3300 0.6602 0.6651 10.3169 94.1789 93.9857 92.3414 100 0.5 20.8322 13.4500 0.6345 0.8487 10.4560 92.6383 94.2789 97.5302 100 1.0 20.4344 13.7293 0.6760 0.7637 10.6245 93.5104 94.0180 92.8476 100 1.5 19.7142 13.7390 0.6794 0.5793 9.8169 95.0808 93.5272 88.0335 100 2.0 19.9400 14.0095 0.6229 0.7174 9.9823 94.0257 94.1265 88.3024 100 2.5 20.2796 14.3546 0.6312 0.7354 10.0105 94.0231 94.0686 87.6498 100 3.0 19.8370 14.3691 0.6080 0.7599 9.9583 93.8302 94.2459 85.8264 100 3.5 19.8470 14.4872 0.5842 0.8122 9.9832 93.4593 94.4717 85.5076 100 4.0 19.7875 14.6897 0.5862 0.8149 9.9863 93.5280 94.4554 84.0143 100 4.5 19.4323 14.2967 0.6851 0.5525 9.8303 95.4914 93.4848 83.0311 100 5.0 19.5085 14.3409 0.7074 0.5367 9.8497 95.6338 93.2993 82.9761 100 145 Table E-20: Product gas analysis and calculation of trial of catalyst with reaction temperature of 8000C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 20.7866 13.1847 0.2490 0.1463 10.3642 98.7054 97.6539 93.1727 100 0.5 20.3380 13.0998 0.2627 0.1061 10.1328 99.0551 97.4729 91.4292 100 1.0 19.9940 13.1015 0.5375 0.0000 9.9305 100.0000 94.8653 89.0216 100 1.5 19.9964 13.0698 0.4492 0.0012 10.1115 99.9893 95.7465 89.2578 100 2.0 19.9838 12.9221 0.3316 0.0634 10.1727 99.4276 96.8432 90.7308 100 2.5 19.5103 13.1266 0.5053 0.0000 9.8196 100.0000 95.1060 86.7019 100 3.0 19.8839 12.9142 0.3857 0.0112 10.1431 99.8988 96.3367 89.9064 100 3.5 19.6414 12.7647 0.3655 0.0178 10.0485 99.8373 96.4903 89.9054 100 4.0 19.8820 13.0404 0.3403 0.0320 10.1941 99.7137 96.7696 89.1931 100 4.5 19.9646 13.2649 0.2449 0.1385 10.2116 98.7819 97.6579 88.8784 100 5.0 19.9984 13.3581 0.2442 0.1162 10.2521 98.9851 97.6735 88.2262 100 146 Table E-21: Product gas analysis and calculation of trial of catalyst with reaction temperature of 8000C Concentration (vol %) Conversion and selectivity (%) Time H2 O2 N2 CO2 CH4 CO CH4 conv CO sel H2 sel O2 conv 0.0 19.2317 0.0000 12.8201 0.6818 0.9390 9.5149 91.4548 93.3135 95.6834 100.0000 0.5 19.5770 0.0000 13.0622 0.4910 0.3907 9.7584 96.5104 95.2095 90.5884 100.0000 1.0 19.8520 0.0000 13.6671 0.4691 0.3474 10.0063 97.0345 95.5219 87.3210 100.0000 1.5 19.6207 0.0000 13.1910 0.4410 0.3448 10.0462 96.9504 95.7949 89.4960 100.0000 2.0 19.3474 0.0000 13.9473 0.5080 0.1937 9.7713 98.3797 95.0580 82.2515 100.0000 2.5 19.5095 0.0286 13.5874 0.5027 0.2109 9.8861 98.1891 95.1611 85.3028 99.5089 3.0 19.6725 0.0000 13.4443 0.4677 0.2088 10.0373 98.1881 95.5478 86.9319 100.0000 3.5 19.7964 0.0000 13.4749 0.4639 0.2178 10.0547 98.1143 95.5897 87.3465 100.0000 4.0 19.6736 0.0000 13.4832 0.4597 0.2082 9.9565 98.1985 95.5867 86.6768 100.0000 4.5 19.8015 0.0000 13.6703 0.4640 0.1977 10.0057 98.3128 95.5682 85.9462 100.0000 5.0 19.6365 0.0000 13.7382 0.4697 0.1831 9.9843 98.4451 95.5070 84.6948 100.0000 147 148 .. .PREPARATION AND ACTIVITY OF Ni- MgO/ α -Al2O3 CATALYSTS IN THE PARTIAL OXIDATION OF METHANE A Thesis Presented to The Faculty of Graduate School College of Engineering De La Salle University In. .. with those remaining in the substrate and this inhibits their sintering, and the high dispersion of Ni inhibits the coke formation that requires large clusters of Ni (Ruckenstein and Hu, 1999)... reported that compared to MgO and NiO, in the MgO/ NiO solid solution Mg(2p) has a lower binding energy than Ni( 2p3/2) The binding energy of Ni( 2p3/2) and Mg(2p) in 9.7 mol% NiO /MgO catalyst prepared