Nghiên cứu phản ứng hydrogen hóa CO bằng các hệ xúc tác lưỡng kim loại ni cu, co cu phân tán trên các chất mang than hoạt tính, mgo, al2o3 theo phương pháp phiếm hàm mật độ tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF EDUCATION NGUYEN BINH LONG RESEARCH THE HYDROGENATION OF CO BY BIMETALLIC CATALYST Ni-Cu, Co-Cu DISPERSED ON CARRIERS OF ACTIVATED CARBON, MgO, Al2O3 ACCORDING TO DENSITY FUNCTIONAL THEORY METHOD Specialization: Theoretical and Physical Chemistry Code: 9.44.01.19 SUMMARY OF CHEMICAL PhD THESIS HA NOI – 2020 The thesis was completed at: Department of Chemistry - Hanoi University of Education Scientific Instructors: Assoc Prof Dr NGUYEN NGOC HA Prof Dr JOHN Z WEN Review 1: Prof Dr Lam Ngoc Thiem - Hanoi University of Science, VNU Review 2: Assoc Prof Dr Vu Anh Tuan - Institute of Chemistry Review 3: Assoc Prof Dr Le Van Khu – Hanoi National University of Education The thesis will be presented to the Board of thesis review at Hanoi University of Education on .h day month year The thesis can be found at: National Library, Hanoi or the library of Hanoi National University of Education LIST OF WORKS PUBLISHED BY AUTHOR Nguyen Ngoc Ha, Nguyen Thi Thu Ha, Nguyen Binh Long, Le Minh Cam Conversion of Carbon Monoxide into Methanol on AluminaSupported Cobalt Catalyst: Role of the Support and Reaction Mechanism - A Theoretical Study 2019, Catalysts, 9(1):6 DOI: 10.3390/catal9010006 (IF = 3.444, Q2) Nguyễn Bình Long, Nguyễn Thị Thu Hà, Lê Minh Cầm, Nguyễn Ngọc Hà Nghiên cứu lí thuyết khả hấp phụ CO H2 Của hệ xúc tác lưỡng kim loại Ni-Cu chất mang MgO(200) phương pháp phiếm hàm mật độ Tạp chí hóa học, 2018, 56, 6e2, 189-193 Nguyễn Bình Long, Nguyễn Thị Thu Hà, Lê Minh Cầm, Phùng Thị Lan, Nguyễn Ngọc Hà Nghiên cứu lí thuyết phản ứng hydrogen hóa CO hệ xúc tác lưỡng kim loại Ni 2Cu2 chất mang MgO(200) phương pháp phiếm hàm mật độ Tạp chí hóa học, 2019, 57, 2e1,2, 108-114 Nguyễn Bình Long, Nguyễn Thị Thu Hà, Phùng Thị Lan, Lê Minh Cầm, Nguyễn Ngọc Hà Nghiên cứu lí thuyết phản ứng hydro hóa CO hệ xúc tác lưỡng kim loại Co2Cu2 chất mang MgO(200) phương pháp phiếm hàm mật độ Phần 1: Giai đoạn hấp phụ hoạt hóa Tạp chí khoa học, Trường ĐHQG Hà Nội, Vol 36 No (2020) 81-89 Nguyễn Bình Long, Nguyễn Thị Thu Hà, Lê Minh Cầm, Nguyễn Ngọc Hà Nghiên cứu lí thuyết phản ứng hydro hóa CO hệ xúc tác lưỡng kim loại Co2Cu2 chất mang MgO(200) phương pháp phiềm hàm mật độ Phần 2: Cơ chế phản ứng Tạp chí khoa học, Trường ĐHQG Hà Nội (accepted) INTRODUCTION The reason for choosing topic With the development of industry, the demand for energy has become increasingly urgent Fossil fuels such as oil and coal with limited reserves have been fully exploited, leading to depletion In addition, the burning of these fuels creates large amounts of CO 2, CO causing environmental pollution, seriously affecting human health Therefore, the search for alternative energy sources is an urgent issue on a global scale Although there have been many empirical studies on syngas metabolism (CO and H2) on single transition metal catalysts or with additional promoter, so far, syngas reaction mechanism on multi-component catalyst systems (metal/promoter/carrier) is still a problem for scientists From a theoretical research perspective, there are also many studies on syngas metabolism on single catalyst systems such as Ni, Co, Cu, etc However, the number of studies on syngas reaction above multi-component catalyst systems, such as bimetal metal catalyst carriers on carriers, are very limited While the research results for these systems, if any, will provide useful information clarifying the role of metal centers, the role of carriers, thereby elucidating the antiapplication Theoretical studies of the syngas transformation reaction on bimetallic catalyst systems can be facilitated by computational chemical methods Thereby, information about geometric structure, electron structure, energy, properties, the role of substances, intermediate products, transition state and interactions can be obtained Therefore, we conduct research on the topic: “Research the hydrogenation of CO by bimetallic catalyst Ni-Cu, Co-Cu dispersed on carriers of activated carbon, MgO, Al2O3 according to density functional theory method” Research purpose Using computational chemistry methods to study the mechanism of hydrogenation CO on the transition metal catalyst systems of Ni, Cu, Co, bimetallic catalysts NiCu, CoCu and catalytic systems bearing cluster on oxide carriers: MgO, Al2O3 and activated carbon (AC); compare and clarify the role of catalyst centers in single or bimetallic catalyst systems; clarifies the role of carriers (MgO, Al2O3 and AC) in the hydrogenation of CO Research tasks a) Researching documents, developing an overview and evaluation of the following issues: - Theoretical basis of quantum chemical problems; thermodynamics and related kinetics; Chemical calculation methods used in the thesis (DFT, CINEB, MD and Monter Carlo simulations) - The situation of studying syngas metabolism reaction on catalysts in the country and in the world; outstanding and unresolved issues b) Carry out studies to calculate the hydrogenation reaction mechanism of CO on catalyst systems: Cluster of Ni, Cu, Co, NiCu, CoCu and catalyst systems on MgO, Al2O3 and AC carriers: - Modeling and optimizing structures of CO, H 2, Ni, Cu, Co, NiCu, CoCu, MgO, Al2O3, AC, Ni/MgO (AC), Cu/cluster systems MgO (AC), NiCu/MgO (AC); Cu/Al2O3, Co/Al2O3, CuCo/Al2O3 - Research, predict adsorption sites, priority responses - Study the adsorption and activation process of CO and H on the above catalyst systems: calculation of adsorption energy values, density distribution, analysis of changes in structural parameters (if any), clarify the nature of the adsorption process (physical or chemical); - Study the CO conversion reactions on the catalyst to create alcohol products (methanol, ethanol) and other organic products (methane, formaldehyde, ): propose and calculate energy parameters for reaction lines, identification of transition states, intermediate products in reaction lines From there, build potential potential surface, evaluate and select priority reaction lines - Evaluate and compare the performance and selectivity of the catalyst systems Scope and object of the study - Substances involved initially: CO, H2 - Possible products of syngas metabolism: methane, methanol, ethanol, formaldehyde, formic acid - Transitional metal clusters: Ni4, Cu4, Co4, Ni2Cu2, Cu2Co2 - Carriers: metal oxides: Al2O3, MgO and activated carbon (AC) Scientific and practical significance of the thesis * Scientific significance: - Using quantum chemical calculation methods, the results of the thesis provide a complete picture at the molecular level of the processes and stages occurring in the hydrogenation of CO on the Metal transition systems: Ni, Cu, Co and bimetallic NiCu, CoCu, contributing to elucidate syngas metabolic reaction; clarifies and explains the role of metal centers, the role of the substance that gives the selectivity and the product of the reaction The results obtained are useful references for scientists, graduate students, students in the field of catalysis - adsorption, chemical calculation * Practical significance: - The results of the thesis are the basis for designing and constructing new catalysts (bimetallic) with high efficiency and selectivity for syngas metabolism to create high-chain alcohol, thereby contributing to the development of developing technology to transform syngas mixture into useful organic products, simultaneously solving two economic and environmental issues New points of the thesis - Studied the stages of adsorption and activation of CO and H 2, and the mechanism of hydrogenation of CO to create different products (methanol, methane, high alcohol), constructing potential surfaces of the reaction Applied on catalyst systems: NiCu/AC, Ni2Cu2/AC, Ni2Cu2/MgO, Co2Cu2/MgO, Co4/Al2O3, Cu4/Al2O3 and Co2Cu2/Al2O3 - Calculation results for the hydrogenation CO on catalyst system show that bimetallic sites effectively reduce the activation energy of CO insertion and hydrogenation reactions to CH3*, resulting in the formation of oxygencontaining C2 products (e.g ethanol) as main products on these positions All the catalysts are all potential catalysts - For the reaction to create ethanol, identified important intermediates that determine ethanol selection are CH3O*, CH2OH*, CH3* and CH3CO* The hydrogenation and dissociation capacity of CH3O*, CH2OH* intermediate particles directly affects methanol selection The selectivity of ethanol also increases with increasing surface area of the bimetallic sites on the catalyst by weakening CO adsorption and preventing methaneization - The most potential and favorable catalyst for ethanol synthesis is proposed as Co2Cu2/Al2O3 system Most reactions on Co2Cu2/Al2O3 catalysts have small Ea and negative ∆E The role of Al2O3 in the hydrogenation of CO has been shown The layout of the thesis Introduction: Introducing the reasons for choosing the topic, the purpose and scope of the research, the new points of the thesis, the scientific and practical significance of the thesis Content: 03 chapters Chapter 1: Introduce the theoretical basis Chapter 2: Overview of research system, empirical research situation and syngas transformation theory in Vietnam and in the world Chapter 3: Research results and discussion Conclusion: Summary of outstanding results of the thesis References Appendix The results of the thesis have been published in articles published in local and international journals Chapter THEORY BASIS Introduction of theoretical basis including the problems of quantum chemical theory and theory of chemical dynamics such as: Schrodinger equation, basic function, introduction of quantum chemical approximation methods, transitional state theory Chapter LITERATURE REVIEW 2.1 Overview of research on syngas metabolism in the world High alcohol synthesis directly from syngas was discovered by two German scientists Frans Fischer and Hans Tropsch in 1923 This process was promoted by many different types of catalysts and many researches on mechanism The reaction was carried out to find a suitable catalyst with high alcohol selectivity Catalysts for high alcohol synthesis can be divided into four main groups: i) Catalytic modification of methanol synthesis process; ii) Catalytic modification of Fischer-Tropsch (FT) process; iii) Catalyst based on Mo; and iv) catalytic system based on Rh 2.2 Researches in our country In Vietnam nowadays, the issue of converting syngas into liquid fuel or alcohol mixture from coal, natural gas or biomass sources has started to attract research attention not only by scientists Studying big industrial corporations However, the research results of the research groups are few (or not) widely published in specialized scientific journals 2.3 The objective of the thesis Most syngas-based ethanol formation studies have focused on singlemetallic or bimetallic systems without carriers due to the computational burden associated with complex reaction networks However, it is clear from empirical research that the addition of bimetal catalysts and the role of carriers are necessary to use normal metals in place of precious metals but can still Selectable ethanol To evaluate the possibility of combining the two metals, we used DFT simulation of all reactions associated with the formation of ethanol from syngas Chapter 3: RESULTS AND DISCUSSION All structural and energetic calculations in this thesis are done by DFT method in the Generralized gradient approximation (GGA), the PBE exchange correlation function, using the DZP base function set, the hypothesis full standard Kleinman-Bylander Troullier-Martins form with cutoff function equivalent to plane wave 2040.75 eV The Brillouin-zone is sampled at point Γ Geometric optimized structures using the Quasi Newton algorithm with a force convergence criterion of 0.05 eV/Å The calculation method is integrated in QUANTUM software, which is a software package that combines SIESTA with NEB and some other features The bond order is calculated by Mayer method The charge of atom is studied based on the Voronoi method Transition state is determined by CI-NEB method 3.1 The hydrogenation of CO by the Ni-Cu catalyst supported on AC 3.1.1 Adsorption of H2, CO on NiCu/AC When we bring the NiCu cluster to AC, we determine the most durable structure, from which research the adsorption of CO and H2 on that structure - Adsorbed H2 on NiCu/AC: When H2 adsorbed on NiCu/AC, H2 was dissociated when adsorbed onto NiCu/AC - CO adsorption on NiCu/AC: The adsorption of CO on NiCu/AC has no dissociation The CO adsorption processes on NiCu/AC are not through transition state, great adsorption energy, Figure 3.1.11 The structures of CO adsorption on NiCu and NiCu/AC so the adsorption process happens smoothly - When CO and H2 adsorbed on NiCu/AC, CO will adsorb first then H will adsorb to the next chemical reaction 3.1.2 Convert CO and H2 on NiCu/AC Table 3.1.8 Adsorption energy and activation energy of CO and H2 conversion on NiCu/AC catalyst (kJ/mol) Ni NiCu Cu Reaction ∆E Ea ∆E Ea ∆E Ea R1 CO(g)+*→CO* -246,6 -261,9 - -180,6 R2 H2(g)+*→2H*(H2*) -66,1 -160,0 25,3 -55,0 R3 CO*+H*→CHO*+* 51,8 93,5 77,4 82,9 89,3 98,9 R4 CHO*+H*→CH2O*+* -51,0 9,6 -94,8 0,3 R5 CH2O*+H*→CH3O*+* -42,3 31,5 -51,8 40,3 -85,4 56,7 R6 CH3O*+H*→CH3OH*+* 117,2 170,7 54,2 150,5 R7 CH3OH*→CH3OH(g)+* 110,9 63,1 R8 CO*+H*→COH*+* 98,0 115,1 R9 CHO*+H*→CHOH*+* 97,3 204,2 0,2 119,1 60,9 190,0 R10 CH2O*+H*→CH2OH*+* 19,0 129,2 -4,2 50,7 R11 CH2O*→CH2O(g)+* 229,5 266,5 R12 COH*+H*→CHOH*+* -21,6 44,3 R13 CHOH*+H*→CH2OH*+* -5,0 27,6 -58,7 35,5 R14 CH2OH*+H*→CH3OH*+* 20,6 150,9 15,8 173,2 R15 COH*+H*→C*+H2O* 220,8 239,6 R16 CHOH*+H*→CH*+H2O(g) +* 89,2 106,6 R17 CH2OH*+H*→CH2*+H2O* -74,8 83,7 R18 H2O*→H2O(g) +* 105,7 55,9 - R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 R31 R32 R33 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 R56 R57 R58 CH*+ H*→CH2*+* CH2*+ H*→CH3*+* CH3*+ H*→CH4(g) +2* CH*+ CO→CHCO*+* CH2*+ CO*→CH2CO*+* CH3*+ CO*→CH3CO*+* CHCO*+H*→CH2CO*+* CH2CO*+H*→CH3CO*+* CHCO*+H*→CHCHO*+* CH2CO*+H*→CH2CHO*+* CH3CO*+H*→CH3CHO*+* CHCHO*+H*→CH2CHO*+* CH2CHO*+H*→CH3CHO*+* CH3CHO*→CH3CHO(g) +* CHCHO*+H*→CHCH2O*+* CH2CHO*+H*→CH2CH2O*+* CH3CHO*+H*→ CH3CH2O*+* CHCH2O*+H*→CH2CH2O*+* CH2CH2O*+H*→CH3CH2O*+* CH3CH2O*+H*→CH3CH2OH*+* CHCH2O*+H*→CHCH2OH*+* CH2CH2O*+H*→CH2CH2OH*+* CHCH2OH*+H*→CH2CH2OH*+* CH2CH2OH*+H*→CH3CH2OH*+* CHCO*+H*→CHCOH*+* CH2CO*+H*→CH2COH*+* CH3CO*+H*→CH3COH*+* CHCOH*+H*→CH2COH*+* CH2COH*+H*→CH3COH*+* CHCOH*+H*→CHCHOH*+* CH2COH*+H*→CH2CHOH*+* CH3COH*+H*→CH3CHOH*+* CHCHOH*+H*→CH2CHOH*+* CH2CHOH*+H*→CH3CHOH*+* CH3CHOH*+H*→CH3CH2OH*+* CH3CH2OH*→ CH3CH2OH(g)+2* CHCHOH*+H*→CHCH2OH*+* CH2CHOH*+H*→CH2CH2OH*+* CHCH2OH*+H*→CH2CH2OH*+* CH2CH2OH*+H*→CH3CH2OH*+* -140,5 4,8 -125,3 39,7 109,0 112,4 50,9 33,2 -36,9 -76,2 -27,0 -76,2 -2,5 -99,5 10,4 193,6 20,5 -15,0 -101,8 -136,4 -46,8 81,6 -34,3 -2,6 -100,4 49,8 72,7 -58,8 51,5 110,7 75,3 23,1 44,8 72,5 49,6 38,7 72,4 81,5 56,4 56,7 80,2 79,4 113,1 146,6 47,9 18,6 79,7 95,6 10,3 -143,4 113,8 -94,9 9,4 -9,6 -143,4 -16,4 37,3 109,0 -5,4 -85,4 -100,4 49,8 123,6 38,5 46,8 113,8 91,9 149,6 90,9 175,7 18,6 79,7 -95,5 94,7 234,8 112,4 -267,8 -29,6 77,1 -26,2 -49,7 124,6 -25,4 -68,6 -59,0 -19,7 -76,1 24,6 233,4 28,7 -0,1 -67,6 53,1 -46,8 -101,7 -96,0 95,4 -61,9 -46,0 -108,1 81,7 108,0 -34,4 59,4 104,6 -74,1 15,9 195,6 -67,2 7,7 -45,3 55,6 -154,4 31,3 87,3 -26,6 -67,6 -108,1 81,7 6,7 218,7 67,1 108,4 58,9 205,3 63,7 43,9 72,5 21,7 109,3 209,6 269,2 79,4 77,9 89,8 121,5 74,8 39,1 22,5 162,2 184,6 132,4 75,4 125,4 161,4 47,1 140,4 51,1 122,6 97,8 226,8 22,5 162,2 R59 R60 R61 R62 R63 R64 CHCHO*+H*→CHCHOH*+* -32,4 58,5 17,7 50,9 CH2CHO*+H*→CH2CHOH*+* 74,6 156,8 38,4 150,5 CH3CHO*+H*→CH3CHOH*+* -10,3 93,8 -109,4 84,2 CHCHOH*+H*→CH2CHOH*+* 71,4 101,0 55,6 140,4 CH2CHOH*+H*→CH3CHOH*+* -16,4 91,9 -154,4 51,1 CH3CHOH*+H*→CH3CH2OH*+* 37,3 149,6 30,0 151,0 Note: The symbol* refers to the adsorbent on the catalytic system or an empty surface position From the calculated results, we propose a convenient reaction pathways for the formation of C2H5OH* from CO as follows: * * * * * CO* 2H CH2O* H CH2OH* H CH2* H CH3* H CH4(g) R3, R4 R20 R10 R17 R21 CO* R24 H2(g) 2H* R2 CH3CO* 3H* R29, R35, R38, R54 CH3CH2OH(g) CO(g) R1 Figure 3.1.22 Reaction network form ethanol on NiCu/AC catalysts The process of calculating 127 reactions shows that the use of Ni-Cu bimetallic supported on AC is completely favorable Bimetallic position reduces energy to reduce activation energy of CO insertion reaction, hydrogenation reactions for intermediates CH3* CH2O(g) CO* CHO* CH2O* COH* CHOH* CH2OH* C* CH* CHCO* CHCOH* CH3* CH4(g) CH3OH(g) CO* CH3COH* CH3CHO* CH3CHOH* CH2CH2O* CH2CH2OH* CH3OH* CH3 CH2CHO* CH2CHOH* CHCH2O* CHCH2OH* CH2CO* CH2COH* CHCHO* CHCHOH* CH2* CH3O* CH3CHO(g) CH3CH2OH* CH3CH2OH(g) CH3CH2O* Figure 3.1.25 The Fischer - Tropsch reaction diagrams of CO with H2 by Ni-Cu catalyst system supported on activated carbon 3.2 The hydrogenation of CO by the Ni2Cu2 catalyst on AC 10 In this section, we have calculated 85 intermediate reaction steps in the proposed reaction mechanism of ethanol synthesis from CO and H2 mixture on a Ni2Cu2 cluster catalyst supported on AC The key to the formation of ethanol on a bimetallic cluster is still the presence of the bimetallic interface, which effectively reduces the activation energy of the CO insertion reaction, the hydrogenation reactions for CH3* Unlike NiCu/AC catalyst (main product is methane and ethanol), Ni2Cu2/AC catalyst can also produce methanol 3.3 The hydrogenation of CO by the Ni 2Cu2 catalyst supported on magnesium oxide (MgO) 3.3.1 Adsorption of H2, CO on Ni2Cu2/MgO The research results have shown the most stable adsorption structure of Ni2Cu2 on MgO, thereby finding the most stable H 2, CO adsorption structure on Ni2Cu2/MgO Figure 3.3.3 Structures Figure 3.3.4 Structures Figure 3.3.5 Structures of Ni2Cu2/MgO (bond of H2 adsorption on of CO adsorption on lengths in Å) Ni2Cu2/MgO Ni2Cu2/MgO 3.3.2 Convert CO and H2 on Ni2Cu2/MgO Table 3.3.5 Energy variation (ΔE, kJ/mol), activation energy (Ea, kJ/mol) of CO conversion on Ni, Cu and Ni-Cu catalyst centers Ni NiCu Cu Reaction ∆E Ea ∆E Ea ∆E Ea R1 CO(g)+*→CO* -257,9 -263,0 -181,1 R2 CO*→C* + O* 266,4 329,1 R3 CO*+H*→CHO*+* 60,3 101,7 87,1 94,1 116,0 126,0 R4 CHO*+H*→CH2O*+* 32,5 72,5 -36,1 64,9 R5 CH2O*+H*→CH3O*+* -144,1 43,7 R6 CH3O*+H*→CH3OH*+* 155,7 278,1 104,7 140,8 R7 CH3OH*→CH3OH(g)+* 43,7 114,8 87,1 R8 CHO*→CH*+O* 98,7 143,3 R9 CH2O*→CH2*+ O* -33,5 116,2 R10 CH3O*→CH3*+O* 21,3 72,0 51,2 111,6 R11 CO*+H*→COH*+* 110,7 189,0 R12 CHO*+H*→CHOH*+* 26,7 48,3 R13 CH2O*+H*→CH2OH*+* -77,9 3,2 54,3 135,7 R14 COH*+H*→CHOH*+* 10,1 143,2 R15 CHOH*+H*→CH2OH*+* 42,6 44,4 -59,7 13,6 14 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 R31 R32 R33 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 15 CH2OH*+H*→CH3OH*+* CH2OH*+H*→CH3OH(g)+* COH*+H*→C*+H2O* CHOH*+H*→CH*+H2O +* CH2OH*+H*→CH2*+H2O* C*+ H*→CH*+* CH*+ H*→CH2*+* CH2*+ H*→CH3*+* CH3*+ H*→CH4(g) +2* CH*+ CO*→CHCO* CH2*+ CO*→CH2CO* CH3*+ CO*→CH3CO* CHCO*+H*→CH2CO* CH2CO*+H*→CH3CO* CHCO*+H*→CHCHO* CH2CO*+H*→CH2CHO* CH3CO*+H*→CH3CHO* CHCHO*+H*→CH2CHO* CH2CHO*+H*→CH3CHO* CH3CHO*→CH3CHO(g) +* CHCHO*+H*→CHCH2O* CH2CHO*+H*→CH2CH2O* CH3CHO*+H*→ CH3CH2O* CHCH2O*+H*→CH2CH2O* CH2CH2O*+H*→CH3CH2O* CH3CH2O*+H*→CH3CH2OH*+* CHCH2O*+H*→CHCH2OH* CH2CH2O*+H*→CH2CH2OH* CHCH2OH*+H*→CH2CH2OH* CH2CH2OH*+H*→CH3CH2OH(g)+* CH2CH2OH*+H*→CH3CH2OH* CHCO*+H*→CHCOH* CH2CO*+H*→CH2COH* CH3CO*+H*→CH3COH* CHCOH*+H*→CH2COH* CH2COH*+H*→CH3COH* CHCOH*+H*→CHCHOH* CH2COH*+H*→CH2CHOH* CH3COH*+H*→CH3CHOH* CHCHOH*+H*→CH2CHOH* 0,484 220,1 75,2 18,7 93,5 84,2 92,9 -59,0 14,3 74,9 13,0 -75,5 91,9 -3,1 44,0 -167,8 17,1 8,5 57,3 -63,8 120,6 -110,7 18,6 -110,0 55,7 177,6 53,1 72,1 60,3 36,7 192,9 67,1 108,0 25,4 76,1 106,5 67,2 78,3 4,6 76,0 119,6 36,2 84,5 37,7 24,7 79,7 4,7 111,1 -48,0 -137,1 20,5 -10,5 33,2 90,9 -54,4 68,2 -4,3 90,6 -50,9 -72,1 42,5 10,5 68,4 -110,7 46,5 157,3 28,7 -25,8 46,1 -50,3 -83,6 177,6 -17,0 72,7 186,7 238,2 20,6 76,1 22,3 100,9 -34,9 21,7 43,6 -23,2 58,7 81,8 -47,0 36,2 -59,9 67,8 1,4 41,5 67,0 -21,2 77,8 -117,2 61,5 -56,3 35,3 78,4 173,9 6,4 122,5 21,0 19,5 77,9 -23,1 39,5 115,5 -162,7 41,6 -21,4 52,3 -39,2 61,5 119,4 79,0 173,6 82,8 119,6 41,3 104,1 -26,7 -11,0 41,4 32,6 -72,7 26,6 67,9 -61,4 181,8 199,4 163,9 26,6 67,9 -65,0 134,3 89,2 9,0 88,9 -24,1 -2,2 132,3 -41,4 24,6 9,9 -73,4 57,1 5,9 85,0 58,1 -61,9 79,5 29,5 91,6 102,4 19,1 102,2 171,1 96,7 99,2 206,6 87,0 175,8 62,5 59,1 144,7 49,1 269,2 58,8 157,6 100,8 40,8 283,3 286,9 133,7 61,5 169,4 179,5 34,5 204,7 306,5 26,5 71,0 65,8 77,8 R56 R57 R58 R59 R60 R61 R62 R63 R64 R65 R66 R67 R68 CH2CHOH*+H*→CH3CHOH* CH3CHOH*+H*→CH3CH2OH* CH3CH2OH*→ CH3CH2OH(g)+* CH3CHOH*+H*→CH3CH2OH(g)+2* CHCHOH*+H*→CHCH2OH* CH2CHOH*+H*→CH2CH2OH* CHCHO*+H*→CHCHOH* CH2CHO*+H*→CH2CHOH* CH3CHO*+H*→CH3CHOH* H2(g)+*→2H*(H2*) H2O*→H2O(g) +* O*+H*→OH* +* OH* +H*→H2O(g) +* -14,0 87,5 -53,9 43,3 78,9 116,5 1,4 81,0 1,4 49,5 -70,8 26,6 -20,2 31,4 76,7 142,4 -7,0 97,2 -154,1 91,1 - 157,5 -8,2 -52,5 30,2 6,8 64,3 -59,8 187,7 66,9 310,7 60,4 138,4 23,1 72,7 172,5 75,0 88,8 144,4 52,9 41,4 52,3 59,3 84,7 128,2 238,0 13,7 89,9 -199,5 89,2 83,4 275,7 Figure 3.3.14 Reaction pathways converts CO on the Ni2Cu2/MgO catalyst to CH3OH*, CH2* 16 Figure 3.3.15 Reaction pathways converts CH2* on Ni2Cu2/MgO catalyst to ethanol Based on the calculation results, we propose a favorable reaction path for the formation of C2H5OH from CO as follows: Figure 3.3.13 Proposed preferred reaction network to form ethanol from syngas mixture on Ni2Cu2/MgO catalyst In this section, we have calculated the activation energy parameters and reaction energy variation of 147 The calculation results show that the Ni2Cu2/MgO catalyst has the ability to catalyze the formation of effective ethanol In addition to the desired product of ethanol, the catalyst also forms methane and methanol (like the Ni 2Cu2/AC catalyst), the role of the MgO has not shown much difference 3.4 The hydrogenation of CO by the Co2Cu2 catalyst supported on MgO 3.4.1 Adsorption of H2, CO on Co2Cu2/MgO Figure 3.4.2 Structures of Co2Cu2/MgO (bond 17 Figure 3.4.3 Structures of H2 adsorption on Figure 3.4.4 Structures of CO adsorption on Co2Cu2 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 length in Å) Co2Cu2/MgO and Co2Cu2/MgO 3.4.2 Convert CO and H2 on Co2Cu2/MgO Table 3.4.6 Energy variation (ΔE, kJ/mol), activation energy (Ea, kJ/mol) of CO conversion on Co, Cu and Co-Cu catalyst centers Co CoCu Cu Reaction ∆E Ea ∆E Ea ∆E Ea CO(g)+*→CO* -231,2 -214,3 -180,9 CO*→C* + O* 216,2 333,7 CO*+H*→CHO*+* 78,8 CHO*+H*→CH2O*+* -0,1 49,8 CH2O*+H*→CH3O*+* 42,4 120,1 CH3O*+H*→CH3OH*+* 102,9 157,3 58,8 92,0 140,8 CH3OH*→CH3OH(g)+* 107,6 96,7 157,3 CHO*→CH*+O* -6,2 296,8 CH2O*→CH2*+ O* -30,0 178,3 CH3O*→CH3*+O* -132,9 100,0 CO*+H*→COH*+* 210,1 266,2 CHO*+H*→CHOH*+* 114,8 128,3 CH2O*+H*→CH2OH*+* 155,0 167,0 CH2O*→HCHO(g) +* 221,7 CH3*+ H*→CH4(g)+2* 38,5 116,8 CH3*+ CO*→CH3CO* 83,5 124,5 CH3CO*+H*→CH3CHO*+* 12,1 100,1 CH3CHO*→CH3CHO(g) +* 235,1 CH3CHO*+H*→ CH3CH2O*+* -1,1 85,2 CH3CH2O*+H*→CH3CH2OH*+* 133,7 274,3 30,0 88,9 CH3CH2OH*→ CH3CH2OH(g)+* 96,4 67,3 107,3 CH3CO*+H*→CH3COH*+* 90,1 105,3 CH3COH*+H*→CH3CHOH*+* -31,6 123,6 CH3CHO*+H*→CH3CHOH*+* 51,7 124,8 CH3CHOH*+H*→CH3CH2OH*+* 100,4 169,4 H2(g)+*→2H*(H2*) -167,7 -157,8 O*+H*→OH* +* -126,2 58,3 OH*+H*→H2O(g) +* 113,9 - 18 CO*+2H*+H2(g) -300 -400 -289,3 (R4) -339,1 -224,3 -339,2 CH2OH*+H* -172,2 (R13) -160,9 (R9) -197,0 (R10) -184,2 -219,1 (R5) -130,6 (R7) CH3OH* CHO*+H*+H2(g) -234,1 -350 -210,8 (R12) -207,8 (R14) -205,0 (R6) CH3O*+H* -200 CHOH*+H2(g) CO*+2H2(g) Energy, kJ mol-1 (R11) -117,5 CH2O*+H2(g) -151,7 -150 -250 COH*+H*+H2(g) -100 -238,2 -297,0 -345,3 CH2*+O*+H2(g) (R8) CH3*+O*+H* -42,3 -50 CH3OH(g) HCHO(g)+H2(g) CO(g)+2H2(g) CH*+O*+H*+H2(g) 0,0 -369,2 (R3) -417,9 -429,9 -450 Figure 3.4.9 Reaction pathways of CO conversion on Co-Cu catalyst centers of Co2Cu2/MgO system form HCHO, CH3OH, CH3* 50 95,6 173,6 (R19) 147,3 142,0 CH3CH2OH* CH3CH2OH 244,7 242,4 183,4 (R20) 349,7 (R21) CH3CH2OH(g) 220,4 (R24) 180,8 * 297,2 (R23) 311,4 (R25) CH3CH2OH* 116,8 (R15) 183,6 (R17) (R22) 188,8 CH3CHO*+H2(g) 100 (R16) 124,5 CH4(g)+O* 150 CH3CO*+H*+H2(g) 200 CH3*+CO*+H*+H2(g) Energy, kJ mol-1 250 CH3COH*+H2(g) (R18) 316,7 (R25) CH3CHOH*+H* 300 355,0 (R21) CH3CH2O*+H* CH3CHO(g)+H2(g) 330,7 CH3CHOH*+H* 350 315,0 306,1 220,9 (R21) 124,5 94,5 83,5 38,5 0,0 -50 Figure 3.4.10 Reaction pathways of CH3* on Co-Cu catalyst centers of Co2Cu2/MgO form CH4, CH3CHO, CH3CH2OH Based on the calculation results, we propose a favorable reaction path for the formation of C2H5OH from CO as follows: 19 Figure 3.4.12 Reaction network give preference to ethanol from syngas mixture on Ni2Cu2/MgO catalyst In this section, we calculated the activation energy parameters and reaction energy variations of 36 reaction steps The calculation results show that the Co2Cu2/MgO catalytic system has the ability to catalyze the formation of effective ethanol In addition to the desired product is ethanol, there are still other products such as methane and methanol 3.5 The hydrogenation of CO by the Co4, Cu4 catalyst supported on Al2O3 3.5.1 Adsorption H2, CO on M4 M4/Al2O3 In this study, the Al2O3 model (104) was selected as the supporter for the metal catalyst We have studied the cluster structure of Co and Cu4, selected the most durable structure and adsorbed on Al 2O3 Then proceed to adsorb H2 on M4/Al2O3 and CO on M4 and M4/Al2O3 to compare and select the most stable adsorption configuration to continue conversion Figure 3.5.5 Structures of CO Figure 3.5.6 Structures of CO adsorption on Co4 and Co4/Al2O3 adsorption on Cu4 and Cu4/Al2O3 3.5.2 Convert CO and H2 on M4/Al2O3 into CH3OH 3.5.2.1 Convert CO and H2 on Co4/Al2O3 into CH3OH Table 3.5.6 Energy variation (ΔE, kJ/mol), activation energy (Ea, kJ/mol) of CO conversion on Co4/Al2O3 catalyst centers Reaction ∆E Ea R1 CO +* → CO* -237,3 R2 H2 +* → 2H* -280,7 R3 CO* + H* → COH* +* 149,1 R4 COH* + H* → CHOH* +* -5,2 83,0 R5 CHOH* + H2(g) → CH2OH* + H* -97,8 2,1 R6 CH2OH* + H2(g) → CH3OH(g) + H* -22,4 173,5 R7 CHOH* + H* → CH2OH* +* 18,6 114,8 R8 CH2OH* + H* → CH3OH(g) +* 47,8 221,2 R9 CO* + H* → CHO* +* 212,2 - 20 R10 CHO* + H* → CH2O* +* -6,9 73,4 Figure 3.5.7b Reaction pathways of can occur through total hydrogenation of CO on the Co4/Al2O3 catalyst 3.5.2.2 Convert CO and H2 on Cu4/Al2O3 into CH3OH Table 3.5.7 Energy variation (ΔE, kJ/mol), activation energy (Ea, kJ/mol) of CO conversion on Cu4/Al2O3 catalyst centers Reaction ∆E Ea R1 CO +* → CO* -238,2 R2 H2 +* → 2H* -145,4 R3 CO* + H* → COH* +* 23,6 188,6 R4 COH* + H* → CHOH* +* -50,7 100,5 R5 CO* + H* → CHO* +* 54,5 87,9 R6 CHO* + H* → CH2O* +* 31,2 54,2 R7 CH2O* → HCHO(g) +* 138,9 168,5 R8 CH2O* + H* → CH2OH* +* -4,0 115,6 R9 CH2O* + H* → CH3O* +* -69,4 71,2 R10 CH3O* +*H → CH3OH* +* 69,1 140,6 R11 CH3OH* → CH3OH(g) +* 117,2 R12 CHO* + H* → CHOH* +* 154,4 R13 CHOH* + H* → CH2OH* +* -87,5 6,8 R14 CH2OH* + H* → CH3OH(g) + 2* 112,5 112,8 21 Figure 3.5.8 Reaction pathways of can occur through total hydrogenation of CO on the Cu4/Al2O3 catalyst In this section, we calculated the activation energy and reaction energy variations of 10 reactions in a proposed methanol synthesis mechanism from the mixture of CO and H2 on Co4/Al2O3 and 14 reactions on Cu4/Al2O3 Calculation results show that both catalyst systems have the ability to convert CO into methanol, but Co4/Al2O3 catalysts have high Ea reactions, while most Cu4/Al2O3 catalysts have Ea not high The study also showed the role of Al 2O3 supporter in catalytic stability 3.6 The hydrogenation of CO by the Co2Cu2 catalyst supported on aluminum oxide (Al2O3) Table 3.6.5 Energy variation (ΔE, kJ/mol), activation energy (Ea, kJ/mol) of CO conversion on Co, Cu and Co-Cu catalyst centers Co CoCu Cu Reaction ∆E Ea ∆E Ea ∆E Ea R1 CO(g)+*→CO* -183,6 - -228,1 - -156,8 R2 CO*→C* + O* 274,2 309,5 R3 CO*+H*→CHO*+* -45,4 28,6 R4 CHO*+H*→CH2O*+* 29,7 73,5 R5 CH2O*+H*→CH3O*+* -117,6 45,5 R6 CH3O*+H*→CH3OH*+* 34,2 108,4 39,9 84,0 R7 CH3OH*→CH3OH(g)+* 103,3 89,2 118,5 R8 CHO*→CH*+O* 291,0 302,9 R9 CH2O*→HCHO(g)+* 205,6 - 22 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 R31 R32 R33 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 CH2O*→CH2*+ O* -97,7 30,5 CH3O*→CH3*+O* -22,0 74,0 52,1 115,4 4,7 74,9 CO*+H*→COH*+* 24,8 119,8 CHO*+H*→CHOH*+* 38,3 148,3 CH2O*+H*→CH2OH*+* -76,3 44,5 CH2OH*+H*→CH3OH*+* 24,5 167,0 CH2OH*+H*→CH2*+H2O -7,4 65,5 CH*+ H*→CH2*+* -101,4 33,4 CH2*+ H*→CH3*+* -141,3 5,0 CH3*+ H*→CH4(g) +2* -4,9 62,7 CH2*+ CO*→CH2CO* 15,5 44,1 CH3*+ CO*→CH3CO* 29,5 89,6 CH2CO*+H*→CH3CO* -194,1 -215,8 41,1 CH2CO*+H*→CH2CHO* -194,4 21,7 -188,6 53,1 CH3CO*+H*→CH3CHO* 11,0 139,8 39,5 89,1 CH2CHO*+H*→CH3CHO* 30,2 145,3 56,8 311,3 CH3CHO*→CH3CHO(g) +* 134,6 130,8 138,7 CH2CHO*+H*→CH2CH2O* -3,1 107,6 11,7 95,4 CH3CHO*+H*→ CH3CH2O* -84,0 12,2 -168,0 7,8 CH2CH2O*+H*→CH3CH2O* -101,3 13,6 -94,3 111,1 CH3CH2O*+H*→CH3CH2OH*+* 71,6 131,0 62,2 134,4 CH2CH2O*+H*→CH2CH2OH* -103,2 54,3 -66,0 102,7 CH2CH2OH*+H*→CH3CH2OH* -62,9 35,1 CH2CO*+H*→CH2COH* -78,4 131,1 -117,0 89,1 CH3CO*+H*→CH3COH* 147,3 71,1 154,2 CH2COH*+H*→CH3COH* -19,0 180,7 CH2COH*+H*→CH2CHOH* 47,4 77,5 CH3COH*+H*→CH3CHOH* -155,1 77,6 CH2CHOH*+H*→CH3CHOH* -154,3 -84,1 125,4 CH3CHOH*+H*→CH3CH2OH* 43,7 174,1 -4,3 150,0 -100,3 86,4 CH3CH2OH*→ CH3CH2OH(g)+2* 99,2 102,5 61,7 84,4 CH2CHOH*+H*→CH2CH2OH* 41,7 94,8 -187,8 CH2CHO*+H*→CH2CHOH* 66,0 152,7 69,2 151,9 CH3CHO*+H*→CH3CHOH* 56,7 73,3 -151,0 21,4 H2(g)+*→2H*(H2*) -53,5 - -193,8 -38,1 O*+H*→OH* +* -9,1 65,5 OH* +H*→H2O(g) +* -138,1 90,0 Based on the calculation results, we have built the reaction pathways and proposed a convenient reaction path for the formation of CH 4, CH3OH, C2H5OH* from CO as follows: 23 Figure 3.6.11 Reaction networks conversion on the Co2Cu2/Al2O3 catalyst In this section we calculated the activation energy parameters and reaction energy variations of 73 intermediate reaction steps in a proposed ethanol synthesis mechanism from a mixture of CO and H Calculation results show that the Co2Cu2/Al2O3 catalytic system has the ability to catalyze the formation of ethanol efficiently In addition, just like when using Ni 2Cu2/AC, Ni2Cu2/MgO or Co2Cu2/MgO catalysts, in addition to the main product, there is still the formation of methane and methanol 3.7 Comparison of CO and H2 conversion on catalyst systems 24 Figure 3.7.1 The hydrogenation reaction pathways on the catalyst systems form CH2*, CH3* and CH3OH Figure 3.7.2 The reaction pathways convert CH2*, CH3* into CH3CH2OH GENERAL CONCLUSIONS By DFT method, through the study of CO hydrogenation on bimetallic catalyst systems on different carriers, we draw some conclusions as follows: 1) Seven potential catalysts have been studied and selected for the conversion of syngas into alcohol: NiCu/AC, Ni2Cu2/AC, Ni2Cu2/MgO, Co2Cu2/MgO, Co4/Al2O3, Cu4/Al2O3 and Co2Cu2/Al2O3, because Ni and Co are favorable for angiogenesis long-chain hydrocarbons and Cu catalyze the formation of oxygen-containing products 2) For NiCu/AC catalyst system: studied and proposed reaction mechanism (127 stages) at active centers (Ni, Cu and Ni-Cu) Research has shown that the position of the Ni-Cu interface effectively reduces the activation energy of CO insertion and the related reactions to CH 3* intermediates, leading to the formation of oxygen-containing C2 products (e.g ethanol) as the main products on these sites; 3) From the study of the NiCu/AC catalyst, expand the research for the remaining catalysts to find the most potential catalyst for ethanol synthesis Co4/Al2O3, Cu4/Al2O3 catalyst systems can catalyze hydrogen reaction to methanol; while bimetallic catalyst systems (Ni2Cu2/AC, Ni2Cu2/MgO, Co2Cu2/MgO Co2Cu2/Al2O3) all have the potential to catalyze ethanol synthesis from syngas The bimetallic catalyst systems show the synergistic effect between the two metals leading to improved efficiency and selectivity in the reaction of creating ethanol from syngas mixture; The carriers alter the electron structure of the catalyst and catalyze the stability 4) Developed reaction paths to form ethanol on all studied systems The important intermediates determining ethanol selectivity are CH3O*, CH2OH*, CH3* CH3CO* The hydrogenation and dissociation reactivity of CH3O*, CH2OH* intermediate particles directly affects the methanol selection The stages of CO insertion and hydrogenation to create CH 3* have a great influence on ethanol selectivity The selectivity of ethanol can be improved by increasing surface coverage of two-metal mixture sites on the catalyst, weakening the CO adsorption strength and suppressing methanation reaction channels 5) The Co2Cu2/Al2O3 catalyst is considered as the most favorable for ethanol synthesis from syngas The reactions that occur on Co2Cu2/Al2O3 catalysts mostly have small Ea and negative ∆E, different from Co2Cu2/MgO catalysts, this shows the role of Al2O3 carrier Thus, studies have clearly shown the synergistic role of bimetal catalyst, reducing the activation energy of CO* and hydrogenation to CH 3*; The role of a carrier changes the electron structure of the catalyst and stabilizes the catalyst in the hydrogenation reaction to ethanol The theoretical results of the hydrogenation CO reaction mechanism forming ethanol on bimetallic catalyst systems not only provide useful information for the design and synthesis of new material systems but also is the basis for the screening of other promising metal catalysts ... Phùng Thị Lan, Nguyễn Ngọc Hà Nghiên cứu lí thuyết phản ứng hydrogen hóa CO hệ xúc tác lưỡng kim loại Ni 2Cu2 chất mang MgO(200) phương pháp phiếm hàm mật độ Tạp chí hóa học, 2019, 57, 2e1,2, 108-114... Cầm, Nguyễn Ngọc Hà Nghiên cứu lí thuyết phản ứng hydro hóa CO hệ xúc tác lưỡng kim loại Co2 Cu2 chất mang MgO(200) phương pháp phiếm hàm mật độ Phần 1: Giai đoạn hấp phụ hoạt hóa Tạp chí khoa học,... Modeling and optimizing structures of CO, H 2, Ni, Cu, Co, NiCu, CoCu, MgO, Al2O3, AC, Ni/ MgO (AC), Cu/ cluster systems MgO (AC), NiCu/MgO (AC); Cu/ Al2O3, Co/ Al2O3, CuCo /Al2O3 - Research, predict adsorption