Fundamental Research

Fundamental research plays an important role in our R&D on F-T catalyst and process technology. Synfuels China has carries out the following fundamental researches:

Theoretical study on the active phase of Fischer-Tropsch synthesis catalyst, Fischer-Tropsch reaction mechanism, structure and performance of catalyst in Fischer-Tropsch product upgrading. Density functional theory is used to predict the chemical and physical properties of Fe-based (Fe-O, Fe-C and Fe-CO) catalyst and Co-based catalyst (noble metal catalyst). Using reasonable theoretical calculation methods, the structure and spectroscopy properties of catalysts are systematically studied under real reaction conditions. The adsorption and dissociation behavior of syngas, hydrocarbons, olefin and oxygen-containing species, and related reaction thermodynamics and kinetics on potential catalyst structure are investigated, including the addictive effect, carrier effect, and catalytic deactivation mechanism. This provides theoretical guidelines for basic studies and experimental work in laboratory.




Research on the preparation of Fe-based and cobalt-based Fischer-Tropsch catalysts and product upgrading catalysts, and structural characterization of catalyst surface and body phase. Based on the latest research results on nano-materials and thin films, nano-level catalyst and thin-layer model catalysts (Fe-based, Co-based product upgrading catalysts) have been prepared on the basis of existing catalyst preparation technologies. The structure and spectroscopy properties of model catalysts are characterized using our UHV, STM, TEM, LEED, NMR, Raman, IR, in-situ XRD, Mossbauer, etc. The characteristics obtained are combined with the theoretical results for us to reveal those active centers on the catalysts and investigate related reaction mechanisms. This provides theoretical guidance for the preparation of industrial catalysts.

Research on the detailed kinetics model for Fischer-Tropsch synthesis mechanism. Multiple two-phase CSTR steady isothermal models has been used to simulate the slurry-bed reactor. Based on CFD fluid dynamics analysis on inner fluid field in the slurry-bed reactor, experimental results from cold F-T reactor model, and operating data from pilot tests and CTL demonstration plants, new software has been developed to simulate all the processes in an indirect CTL plant, using large-scale slurry-bed F-T reactor and related reaction mechanisms based on the characteristics of F-T catalyst.

Synfuels China fundamental research team has published more than 500 scientific articles in various peer-reviewed journals, including J. Am. Chem. Soc., Angew. Chem. Int. Ed. J. Catal., ACS catalysis, J. Phys. Chem. A (B, C), Surf. Sci. In addition, Synfuels China has prepared three invited book chapters in English and one invited chapter in Chinese.

Oil processing technology
Since the primary products from Fischer-Tropsch (F-T) synthesis mainly consist of straight chain hydrocarbons, which are sulfur-free, nitrogen-free, and low aromatics content, Synfuels China has carried out research on product upgrading technology (including both catalyst and process), including hydrotreating, hydro-isomerization, hydrocracking wax refining, by-product recovery from F-T reaction water, and production of derived-chemicals etc. Moreover, Synfuels China has worked on the characteristics of F-T products and oil-blending technology, and further developed the product standards for F-T liquid fuels and F-T wax product.
Gasoline-max technology
Synfuels China's Gasoline-Max Technology is designed for the production of 92 - 98# clean gasoline products. Nearly sulfur-free clean gasoline product is obtained by blending products from hydrocracking of F-T wax, tertiary olefin etherification, and hydroisomerizing of light straight-chain alkanes.

Process
Synfuels China Gasoline-Max Technology selectively converts F-T heavy wax and light alkanes to gasoline product through fluidized-bed, fixed-bed, catalytic distillation and moving-bed. The process is described below:
• F-T heavy wax is hydrocracked to tertiary-olefins-rich gasoline and gas products on the surface of zeolitic catalyst in a FCC reactor;
• The tertiary olefins are etherified with methanol via catalytic distillation in a fixed-bed reactor to produce high octane ether compounds;
• Light straight-chain alkanes from F-T synthesis is catalytically reformed to aromatics in a moving-bed reactor, which can be used for the blending of gasoline products;
• FCC gasoline, etherified gasoline, and reformed gasoline components are blended to produce final clean gasoline product.

History
2012  Catalytic reforming of light straight-chain alkanes in a fixed bed reactor in laboratory; Fluid catalytic cracking of F-T wax in a fixed fluid-bed reactor using traditional FCC catalyst;
2013  Catalytic reforming of F-T short-straight-chain alkanes in a fixed bed reactor in laboratory; Scale-up of F-T heavy wax fluid catalytic hydrocracking process in a riser reactor using traditional FCC catalyst;
2014  Optimization of the catalyst for F-T short-straight-chain alkanes reforming; R&D on catalyst  for hydrocracking of F-T wax;

Advantages
Synfuels China's Gasoline-Max Technology is designed for the production of 92 - 98# clean gasoline products, with the following advantages compared with traditional petroleum-based gasoline products:
• Nearly sulfur free in the final gasoline products
• Lower aromatics content
• Lower emission of pollutants and particulates
• Improved economic benefits

Diesel-max technology
Synfuels China’s Diesel-Max Technology is designed for the production of 0 - 20# clean diesel products. Based on the characteristics of indirect CTL intermediate products, light olefin and heavy hydrocarbon are efficiently converted to intermediate products via olefin polymerization, hydrotreating, hydrocracking, and hydroisomerization. Meanwhile, straight-chain alkanes are converted to branched-chain alkanes. This maximizes the yield of diesel products, with by-product of aromatic-low naphtha.

The Diesel-Max Process Technology uses fixed-bed reactors for olefin polymerization, hydrotreating, hydrocracking, and hydroisomerization of F-T intermediate products. The technology has the following features:
• Hydrogenation process using non-sulfur catalyst
• Hydrocracking process using non-sulfur catalyst
• Heterogeneous coagulation depression process using non-noble metal catalyst
• Oligomerization process paired with C3-C9 olefin
• Suitable for the converting of F-T syncrudes (C3-C120 hydrocarbons)
• Proprietary catalyst technology for the upgrading of F-T syncrudes

History
2011   R&D on Diesel-Max Technology started
2013   Optimization of catalyst preparation, large-scale catalyst production
2014   Catalyst was used in Yitai CTL demonstration plant
2015   R&D on the second generation catalyst

Advantages
Synfuels China’s Diesel-Max Technology is designed for the production of 0#~-20# clean diesel product, with the following advantages:
  • Sulfur-free in the product upgrading process
  • High diesel yield from wax via hydrocracking process
  • High activity for dimeric-hydrocarbons from light olefin via oligomerization process
  • High branched-chain alkanes yield via non-noble hydroisomerization process

Heavy oil upgrading technology
The Heavy Oil Upgrading Technology developed by Synfuels China is mainly for the production of blending components for gasoline and diesel products. The technology consists of four sub-processes - dissolution, hydrotreating, hydrocracking, and solvent recycling processes. It converts the polycyclic aromatics in heavy oil to mono-cyclic and di-cyclic aromatics, which can be used for the blending of gasoline and diesel products. This technology is suitable for the processing of residual oil, coal tar or ethylene tar.

Process
The Heavy Oil Upgrading Technology is mainly used for the production of gasoline and diesel blending components, including the following sections (Figure.1):
• Mixing of heavy oil and solvent oil
• Filtering of residues from the mixed oil, and centrifugal dehydration
• Pre-hydrotreating of filtered and dehydrated oil
• Hydro-cracking of the oil mixture
• Separation of gasoline/diesel distillates, solvent oil and tail oil
• Recycling of solvent oil and tail oil to the dissolution unit  

Advantages
Synfuels China's Heavy Oil Upgrading Technology has the following advantages:
• Good feedstock adaptability
• No fractionation is required for the removal of tail oil from the feedstock
• High yield of gasoline and diesel components
• Solvent oil can be recycled
• Low energy consumption

Technical Support
Synfuels China provides the following technical support:
• R&D on solvent oil, catalyst and its optimization
• R&D on the process technology and its optimization
• Exploring low cost production scheme

                                       

Product analysis

There are many large-scale characterization instruments in Synfuels China, including chemical adsorption instrument, physical adsorption instrument, Mössbauer instrument, high-resolution transmission and scanning electron microscopy, GC-MS, FTIR, etc. These instruments have been used for the analysis of the surface and bulk structure of heterogeneous catalysts, in order to understand how the structure of F-T synthesis catalyst affects its products and to solve other critical and fundamental scientific and technological issues in F-T synthesis.

Due to the differences between indirect CTL products and traditional petroleum-based liquid fuels, Synfuels China has also carried out researches on the analysis of the composition of indirect CTL liquid fuels and wax, related performance tests, on-line monitoring and analysis of feedstock and process and products, to provide reliable operation data for the quality control of F-T production process. Meanwhile, Synfuels China has developed relevant analytical standards and test methods.






Process integration

Synfuels China has developed its proprietary Medium Temperature Slurry-bed Fischer-Tropsch Process (MTSFTP) technology. It converts qualified syngas, which could be derived from coal, natural gas or biomass, into sulfur-free clean diesel products, with high diesel yield, low methane selectivity, and high thermal efficiency. Therefore, the MTSFTP technology improves the economic benefits of a CTL or GTL plant.

Process:
Coal-based MTSFTP technology consists of three units - syngas production unit including coal gasification and syngas purification, Fischer-Tropsch synthesis unit which consists of Fischer-Tropsch synthesis and products separation, product upgrading where F-T syncrudes are upgraded into clean diesel, naphtha, and LPG. It has the following key features:


• High activity and stability of cheap iron-based F-T catalyst;
• The proprietary Medium Temperature Slurry-bed F-T Reactor greatly improves the thermal efficiency;
• The proprietary product upgrading technology produces high quality clean diesel product free of sulfur and nitrogen;
• All the processes are integrated and optimized to minimize the fixed investment on equipment.
• Detailed studies have been carried out on every technical issue, and all key equipment are optimized on the basis of the first principles.
Research and development
• 1980-1997 Shanxi Institute of Coal Chemistry(SXICC), Chinese Academy of Science (CAS), carried out R&D on Fe-based F-T technology using fixed-bed reactor.
• 1997-1999 Research on the hydrodynamics and kinetics of slurry-bed reactor F-T technology under the direction of Prof. Li Yongwang, research fellow of SXICC, CAS. SXICC II                    A-B catalyst was successfully developed.
• 2000-2004 Successful 15-20 bbl/d pilot test using the MTSFTP technology.
• 2005-2012 Three 4000 bbl/d demonstration CTL plants using MTSFTP technology were constructed in Inner Mongolia and Shanxi, and then operated at full load.
• 2013-present Three large-scale commercial CTL plants are under construction, and will be started up soon.
Technical advantages:
• Catalyst loading is reduced to 1/4 of normal loading due to the high activity of proprietary F-T catalyst. This lowers catalyst attrition and reduces the operating cost in the plant.
• The 30 bar by-product steam from F-T synthesis can be recovered due to the high operating temperature in the slurry-bed reactor, improving the total thermal efficiency of the whole plant.
• The oxygenates content, especially acid content in F-T syncrudes, is greatly reduced. This contributes to the high quality of diesel product, and reduces the fixed investment on equipment.
• The MTSFTP technology is flexible, and can be integrated in CTL, GTL, and BTL plants.


Fine chemical engineering
Synfuels China carries out R&D on hydrogenation, dehydration, and coupling reaction in the fine chemical engineering. Maleic anhydride, furfuraldehyde and other feedstock are used to produce fine chemical products such as GBL, THF, 2-MF and 2-MTHF. In addition, a new process has been developed for the production of ethylene glycol via the catalytic hydration of dimethyl oxalate, using a new copper-based catalyst which has high activity, high selectivity and long life. Among these, the R&D work on the coupling technology for the  production of GBL and 2-MF has won the Second Prize of National Technological Invention


Hydrogenation of maleic anhydride
Fine chemical products such as γ-butyrolactone, 1, 4 butanediol, and tetrahydrofuran can be produced through the hydrogenation of maleic anhydride. Comparing with traditional “Hydrogenation of maleic anhydride esterification”, Synfuels China's direct hydrogenation process of maleic anhydride in vapor phase eliminates the esterification step. Consequently, it shortens the whole process, and reduces production cost. A new generation of high-performance copper-based catalyst has also been developed for the selective production of  either γ-butyrolactone or tetrahydrofuran.
Technical development milestones:
• 1992-2001 Basic research on the hydrogenation of maleic anhydride (furfuraldehyde) and butanediol dehydrogenation in a fixed bed reactor.
 • 2002-2004 Integration and optimization of hydrogenation, dehydrogenation and coupling processes in fixed-bed reactor, and industrial demonstration.
• 2004-2014 Process optimization, engineering design, commercial application, and scale-up of catalyst production.                                            
                                           
The low-pressure maleic anhydride hydrogenation technology has been promoted and applied in Inner Mongolia, Anhui, and other areas. The 5000 t/a γ- GBL unit in Inner Mongolia has achieved remarkable economic and social benefits. A new 10,000 t/a γ- GBL facility has been built in Anhui after further integration and optimization of the technology based on previous experience.
Furfuraldehyde hydrogenation technology
Furfuraldehyde is an important derivative of furan ring. It has active chemical properties, which can produce many derivatives through oxidization, condensation and other reactions. It is widely used in compound plastic, pharmacy, pesticide and other industries. Synfuels China technology selectively convertes furfuraldehyde into 2-methyl furan, 2-methyl tetrahydrofuran and other chemicals through hydrogenation. For example, the main product is 2-methyl furan using Cu-based catalyst, while precious-metal-based catalyst mainly produces furan and tetrahydrofuran.
Imethyl oxalate hydrogenation
The hydrogenation of imethyl oxalate is a key step in the “coal to glycol” process. Due to the low activity and short life of current imethyl oxalate hydrogenation catalysts, Synfuels China developed a new generation of copper-based catalyst for imethyl oxalate hydrogenation. The new catalyst has steady performance and can be regenerated, with a productivity of  0.15-0.3g glycol /g-cat/h and glycol yield of greater than 95%, and a life time of over 2 years.
Technical development milestones:
• 2007-2011 Basic research on dimethyl oxalate ester hydrogenation in a fixed-bed reactor
• 2012-2013 Integration and optimization of dimethyl oxalate ester hydrogenation in a fixed-bed reactor
• 2014-2015 Scale-up of catalyst production technology for dimethyl oxalate ester hydrogenation in a fixed-bed reactor
                                           
Based on research on hydration, dehydration and coupling reactions, high-quality catalyst has been developed based on the hydrogen spillover theory.                                            
                                           
Fifteen patents in fine chemical engineering has been granted to Synfuels China, with more than 50 publications in top English journals. More than 20 PhD and master candidates have graduated with excellent results. Synfuels China has been awarded the second prize of National Technological Invention, and the first prize in technological invention of the Petrochemical Association, and the second prize of Shanxi Provincial Technology, etc.

Multistage liquefaction technology

Synfuels China has developed its proprietary multistage liquefaction technology. This technology combines low temperature pyrolysis technology and modern gasification technology with advanced slurry bed F-T synthesis technology, and can improves the overall energy efficiency of a CTL plant from 38%-43% to 50-55%. A 1 t/h pilot plant has been built in 2010, and several pilot tests have been carried out.

During the multistage liquefaction process, feed coal (or heavy oil, or biomass) is first partially hydrogenated under moderate conditions to extract some light oil; the remaining semi-coke residue is then gasified to produce syngas. The syngas is converted to liquid fuels through Fischer-Tropsch synthesis. Steam at different levels from the gasification and Fischer-Tropsch synthesis units is used for the preheating and dehydration of coal (heavy oil, biomass and other raw material). The F-T liquid fuel is blended with light oil from the partial hydrogenation process to produce final diesel and gasoline products.
Technology research and development process
• 2002-2008 R&D on multistage liquefaction technology in laboratory.
• 2008-2009 Construction of a 1 t/h pilot plant.
• 2010-2014 Pilot tests using brown coal, bituminous coal, coal tar, and heavy oil as feedstock.
Advantage：
• The overall energy efficiency could be increased from 38-43% using indirect liquefaction technology to 50-55%.
• The operating conditions are much milder than those for direct liquefaction technology. This enables the steady operation of multistage liquefaction process.
• The oil products from the multistage liquefaction process can be easily refined, and  used for the blending of final high quality gasoline and diesel products.

Water treatment technology

Various waste water is produced in coal chemical processes, such as gasification black-water, Fischer-Tropsch synthesis water, and wastewater from catalyst production, etc. The waste water needs to be treated effectively to meet the requirements of environmental protection and to improve the economic benefits of the plant by recovering useful products from the waste water. In addition to traditional distillation and oxidative degradation methods, Synfuels China has carried out R&D on new water treatment technologies such as freeze concentration method, hydrate method, and heat pump method.

Freeze Concentration Technology
The freeze concentration water treatment process developed by Synfuels China is based on the principle of solid-liquid equilibrium to separate impurities from waste water. The wastewater is first cooled, then exchanges heat with low temperature refrigerant in a specially-designed device. The treated water is cooled, forming ice crystal, which grows further and has high purity after washing. Portion of the concentrated solution is mixed with the feed intake, and the remaining solution is discharged for further treatment through other process.
Advantages：

• The technology can be used for the wastewater treatment in many processes.
• Treated water has high purity.

Hydrate technology
Synfuels China developed the Hydrate Water Treatment Process. It utilizes the formation of hydrate from certain small molecule gas and water at certain temperature and pressure to realize the separating of impurities from wastewater. Wastewater is first cooled, and contacts certain small molecule cryogenic substance to form hydrate and concentrated solution in a special device, followed by solid-liquid separation. The hydrate is separated from the solution, then broken up to produce high purity water and small molecular gas in another device. Portion of the concentrated solution is mixed with feedstock, and the remaining part is discharged for further processing through other processes.
Advantages：

• Mild operating conditions for hydrate formation
• Can be applied in many industries
• Treated water has high purity

MVR technology
Heat pump distillation process is based on the principle of vapor-liquid equilibrium in order to separate impurities from waste water, and steam is cycled to improve heat efficiency. Steam from the top of the evaporator is compressed through steam engine and then exchange heat with wastewater feed. The waste water is heated and partially vaporized in the evaporator. Portion of concentrated solution is mixed with the waste water feed, and the remaining is discharged for further processing through other processes
Advantages：

• Mature technology.
• The equipment is easy to be manufactured.
• The process is controlled automatically.

Research on coal gasification

Synfuels China is developing a new coal gasification technology. Carbonaceous solid material is partially oxidized by oxygen and steam under certain temperature and pressure to form crude syngas, which is then shifted and purified to produce syngas with high H2/CO ratio, suitable for Fischer-tropsch synthesis, methanol synthesis, and other coal conversion processes.  

The gasification process is as follows. Carbonaceous solid powders are transported by a solid pump into the gasifier near its burner, where the powder is mixed with steam and oxygen to produce crude syngas under certain temperature and pressure. Ash in the coal drops downwards under gravity, and became slag in the slag sink in the gasifier. Melted ash is entrained by the high-temperature gas into the high-temperature and low temperature quench zones in the upper part of the gasifier, and solidified into solid dust. Portion of the solid dust drops down to the gasification zone below, and the remaining dust is carried out of the gasifier with syngas through the top outlet of gasifier. Quenched crude syngas is routed for further processing. The gasification technology has several features. The gasifier has a capacity of 4000 t/d. Solid pumps are used for the transportation of coal powder. In addition, water cooling walls are adopted, and burners are allocated on the side-wall, and internal quench zones are configured.
Technical advantages:
• Large single capacity.
• High efficient solid pumps are used for the transportation of coal powder without carrying gas.
• High carbon conversion rate.
• High H2/CO ratio in the produced syngas.
• Optimized treatment of gasification waste water.

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