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  1. 1. Ganesh Pidathala Sekar Sebastian A. Avella E. 1 POLITECNICO DI MILANO School of Industrial Engineering - Campus Piacenza Master of Science Energy Engineering for an Environmentally Sustainable World Prof. EnricoTronconi Fundamentals of chemical processes for energy and the environment February 2014
  2. 2. WHAT IS SYNGAS? The term Syngas is derived from (Synthesis Gas) is used for describing a mixture containing H2 and CO and very often amounts of CO2 and CH4. Syngas is the direct end-product of the gasification process. Though it can be used as a standalone fuel, the energy density of Syngas is only about 50 percent that of natural gas and is therefore mostly suited for use in producing transportation fuels and other chemical products. As its unabbreviated name implies, Synthesis gas is mainly used as an intermediary building block for the final production (synthesis) of various fuels such as synthetic natural gas, methanol and synthetic petroleum fuel (dimethyl ether – synthesized gasoline and diesel fuel). In a purified state, the hydrogen component of Syngas can also be used to directly power hydrogen fuel cells for electricity generation and fuel cell electric vehicle (FCEV) propulsion. 2
  3. 3. APPLICATIONS  In addition to using Syngas to directly manufature products, through various chemical processes and absorption methods, each individual component of Syngas can be isolated and/or purified for other uses or disposal:  Hydrogen – electricity generation and transportation fuels  Nitrogen – fertilizers, pressurizing agents  Ammonia— fertilizers  Carbon monoxide – chemical industry feedstock and fuels  Carbon dioxide – injected into sequestration wells  Steam – turbine drivers for electricity generation 3
  4. 4. CHEMICAL COMPOSITION Substance Composition (%) H2 20-40 CO 35-40 CO2 25-35 CH4 0-15 N2 2-5 The composition of syngas is highly dependent upon the inputs. A number of the components of syngas cause challenges which must be addressed at the outset, including tars, hydrogen levels and moisture. Hydrogen gas is much quicker to burn than methane, which is the normal energy source for gas engines. Range of composition of Syngas 4
  5. 5. Fischer-Tropsch example The basic reaction for formation is: For example, when octane, a component of gasoline, is formed, Equation becomes Similarly, for the formation of olefins, For ethylene formation, Equation becomes The other type of main reaction that occurs in this process is the water- gasshift reaction 5
  6. 6. INDUSTRIAL PRODUCTION OF SYNGAS: PROCESS TECHNOLOGY Steam reforming Autothermal reforming or oxidative steam reforming Non catalytic Partial oxidation Compound Reforming Method Catalytic Partial Oxidation 6
  7. 7. STEAM REFORMING (SR) Cm Hn + m H2 O = m CO+ (m + n 2) H 2 Jianjun Zhu Catalytic. SR Process. Partial Oxidation of Methane to Synthesis Gas 7
  8. 8. AUTOTHERMAL REFORMING (ATR)  When the ATR uses carbon dioxide the H2: CO ratio produced is 1:1. 2 CH4 + O2 + CO2 → 3 H2 + 3 CO + H2O  When the ATR uses steam the H2: CO ratio produced is 2.5:1. 4 CH4 + O2 + 2 H2O → 10 H2 + 4 CO 8
  9. 9. Other Processes  Compound reforming Method o The compound reforming method combines the steam-reforming reactor with the automatic-thermal reactor. o A major feature of this method is that the early-stage steam reforming reaction and the late-stage automatic-thermal reforming reaction take place in separate devices. o The advantage, as a result, is that low-pressure gas at the outlet of steam reforming reaction can be transformed into high-pressure gas by means of automatic-thermal reforming. o In addition, costs are reduced because a compressor is not required. o The disadvantages, on the other hand, are that there are two reactors and construction costs are high 9
  11. 11. PARTIAL OXIDATION OF HYDROCARBONS All hydrocarbons are possible as feedstocks. Since no water is added, the H2/CO ratio is lower than compared with SR or ATR. Partial oxidation of natural gas is used in small plants Reaction T between 1200– 1600 C and P up to 150 bar. The concentrations of different compounds in the product mixture are determined by several equilibria, which are quickly tuned in at these high temperatures. Partial oxidation can be performed with or without a catalyst. With catalyst, reaction T can be lower, reactions still reaching equilibrium, since catalyst lowers the activation energies. 11
  12. 12. Important considerations Development over the years has been to minimize the use of steam in reforming due to the following disadvantages:  Endothermic reactions  The product gas has a H2/CO ratio of 3  Steam corrosion problems  Costs in handling excess H2O The trend is to move from steam reforming to “wet” oxidation (autothermal reforming) to “dry” oxidation. The dry oxidation is the partial oxidation ( of methane for example). 12
  13. 13. NON-CATALYTIC PARTIAL OXIDATION OF HYDROCARBONS PROCESS DESCIPTION-REACTIONS Producing syngas from heavy hydrocarbons, including deasphalter, pitch and petroleum coke. Feed is pre-heated and then mixed with O2 within a burner; after ignition, reactions occur inside a high T combustion chamber producing an effluent that contains various amounts of soot, depending on feedstock composition. Reactor exit gas T are comprised between 1200-1600°C. Syngas has to be cooled and cleaned within a “washing” section for impurities. ISSUES-PARALLEL REACTIONS The high temperature (1100-1400°C) heat recovery in POx is not very efficient. Oxygen Feed Syngas 13
  14. 14. NON-CATALYTIC PARTIAL OXIDATION OF HYDROCARBONSADVANTAGES  Possibility of utilizing a “low value” feedstock.  The reaction is exothermic (energy consumption is less)  Environmentally friendly in terms of exhaust gases: little NOx production DISADVANTAGES  The oxidation step is highly exothermic reaction, reducing the energy content of the fuel  Cost of reaction materials are high  Soot can easily emerge in the non-catalytic POX process 14
  15. 15. CATALYTIC PARTIAL OXIDATION OF HYDROCARBONSPROCESS DESCIPTION-REACTIONS  The catalytic partial oxidation process has captured wide attention as a noteworthy method that can drastically reduce production costs in the future. ISSUES-PARALLEL REACTIONS  Curtailment of heat generation and removal of reaction heat  Control of conversion rate through equilibrium management 15
  16. 16. CATALYTIC PARTIAL OXIDATION OF HYDROCARBONS THERMODYNAMICS ASPECTS (Methane Example) Saleh A. Al-Sayari. The Open Catalysis Journal, 2013, 6, 17-28 16 1 2 3
  17. 17. CATALYTIC PARTIAL OXIDATION OF HYDROCARBONS KINETICS MODEL DEVELOPMENT Carlo Rudy Harold de Smet. Partial Oxidation of Methane to Synthesis Gas 17
  18. 18. CATALYTIC PARTIAL OXIDATION OF HYDROCARBONS Possible reaction sequence for dissociative methane adsorption Carlo Rudy Harold de Smet. Partial Oxidation of Methane to Synthesis Gas 18
  19. 19. Catalysts used for Partial oxidation of methane  The first row of transition metals (Ni, Co) and precious metals (Ru, Rh, Pd, Pt, and Ir) have been reported as active catalysts for CPOM .  The relative rates of carbon deposition were in the order Ni>Pd>Rh>Ru>Pt, Ir  Carbon deposition is a major issue on nickel catalysts, which may reduce the number of active sites. Heavy carbon formation may even increase the pressure on the feed side or foul downstream process equipment. 19
  20. 20. CATALYTIC PARTIAL OXIDATION OF HYDROCARBONS ADVANTAGES  High reaction rates  Allows high gas velocities while still acheiving thermodynamic equilibrium  Prevents high temperatures and elimínate termal runaway.  Small size reactor ISSUES SURROUNDING CPOX  Improvement of heat resistance of catalyst  Improvement of Coking resistance of the catalyst  Reduction of costs 20
  21. 21. PROCESS OF PRODUCTION Luca Basini Topsoe Catalysis Forum, Aug ., 2006 - Aug 21
  22. 22. ADVANCES AND NEW DEVELOPMENTS  Distinguishing characteristics of the catalytic partial oxidation method  Reaction route of catalytic partial oxidation  Trends in research on catalytic partial oxidation: Direct route catalyst  Process of direct route catalytic partial oxidation  Two-stage route catalyst 22
  23. 23. COMMERCIAL SPECIFICATIONS The table presents an evaluation of the economy of five types of synthetic gas production equipment SMR POX ATR CR CPOX Natural gas consumption volume (GJ/t-MeOH) 32 31.6 30.6 30 (29-30) Oxygen consumption Volume (m^3/t-MeOH) 530 460 280 270-300 CO2 emissions Volume (10^3 t/y) 380 375 355 290 250-270 Relative costs 100 95 85-95 80-85 70-80 23
  24. 24. Synopsis  The distinguishing characteristics of the catalytic partial oxidation method are that energy consumption is slight, that the reaction speed is rapid and that no soot or other unnecessary byproducts are produced.  The issues surrounding this method are improvement of heat resistance and coking resistance of the catalyst and reduction of costs.  Carbide catalysts and metal oxide catalysts of high oxygen ion mobility (permeation) are being developed in order to improve the process.  The economy of the syngas production process by the CPOX method, assuming the process has been completed, is forecast to yield a 30% reduction in costs at most as compared to the steam reforming method.  Research is expected to continue from the standpoint of practical application 24
  25. 25. REFERENCES Ke Liu. Chunshan Song. Velu Subramani. Hydrogen and Syngas Production and Purification Technologies Jianjun Zhu. Catalytic Partial Oxidation of Methane to Synthesis Gas over ZrO2-based Defective Oxides C. W. MONTGOMERY, E..B. WEINBERGER, AND D. S. HOFFMAN. Thermodynamics and stoichiometry of synthesis gas production Carlo Rudy Harold de Smet. Partial Oxidation of Methane to Synthesis Gas: Reaction Kinetics and Reactor Modelling Gaetano Iaquaniello, Elena Antonetti, Barbara Cucchiella, Emma Palo, Annarita Salladini, Alessandra Guarinoni, Andrea Lainati and Luca Basini. Natural Gas Catalytic Partial Oxidation: A Way to Syngas and Bulk Chemicals Production Michael J. Gallagher, Jr.. Partial Oxidation and Autothermal Reforming of Heavy Hydrocarbon Fuels with Non-Equilibrium Gliding Arc Plasma for Fuel Cell Applications Saleh A. Al-Sayari. Recent Developments in the Partial Oxidation of Methane to Syngas Yoon Cheol Yang, Mun Sup Lim, Young Nam Chun. The syngas production by partial oxidation using a homogeneous charge compression ignition engine R. Lanza a,b, P. Canu b, S.G. Ja¨ra˚ s .Partial oxidation of methane over Pt–Ru bimetallic catalyst for syngas production Wenjuan Shan a,*, Matthieu Fleys a, Francois Lapicque b, Dariusz Swierczynski c, Alain Kiennemann c, Yves Simon a, Paul- Marie Marquaire a. Syngas production from partial oxidation of methane over Ce1XNiXOY catalysts prepared by complexation– combustion method Cosme Huertas, Maria Luisa. Tecnologias de produccion de hidrogeno a partir del reformado de queroseno para las aplicaciones aeronauticas Luca Basini Topsoe Catalysis Forum, Aug ., 2006 – Aug. H2 generation using SCT CPO SCT- 25