A Technological Perspective for Catalytic Processes Based on Synthesis Gas

Continuously increasing oil prices, a dwindling supply of indigenous petroleum, and the existence of extensive coal reserves has made the conversion of coal to chemicals and clean-burning fuels an increasingly important part of the national energy programs for a number of industrial nations. In particular, there is a growing interest in the production and use of synthesis gas as a feedstock for the manufacture of fuels and chemicals. Most of the proposed routes are catalytic in nature, and are directed at overcoming the limitations of Fischer-Tropsch chemistry, especially selectivity. Over the past several years, research efforts have led to new selective routes to various fuel fractions; to petrochemical feedstocks including light olefins and various aromatics; to commodity chemicals such as ethylene glycol, ethanol, and acetic acid; and to a number of other fuels and chemicals.     

Chemical Coal Cleaning Assessments at Gulf

Abstract

Extensive work has been conducted at Gulf Research & Development Company over the past 5 years to assess the feasibility of commercializing chemical coal cleaning technologies. Elements of this work are reviewed in this paper. It is concluded that the use of chemical cleaning will await the development of markets for premium coals and the start of new market-oriented strategies by coal companies. The trend by electric utilities toward the use of more efficient fuels and the need to pay out high cost coal reserves may force coal companies to develop premium fuels for improving market share. Significant use of chemical methods in coal preparation is a distinct possibility in the future because of developments now under way in the use of coal as an alternative hydrocarbon feedstock in chemicals and fuels applications. The potential for chemical preparation of low-ash and low-sulfur coal for these new applications is discussed.     

高效、清洁、高附加值原则指导下适度、有序发展煤化工产业

针对我国可持续发展面临的能源瓶颈,指出适度、有序发展煤化工产业是我国现有能源结构环境下的必然选择。在低碳理念指导下,提出了煤炭资源的分质利用原则、高能效利用原则、综合利用原则、因地制宜利用原则和高附加值利用原则,比较分析了煤的各种化学转化途径,阐述了含氧醇醚材料替代石油路线、煤制芳烃、煤/天然气/煤层气制备乙炔等具有前景的清洁、高效转化过程,期望为煤化工产业的健康、有序发展提供科学思路。     

Recent advances on the reduction of CO2 to important C2 + oxygenated chemicals and fuels

The chemical utilization of CO₂ is a crucial step for the recycling of carbon resource. In recent years, the study on the conversion of CO₂ into a wide variety of C_2 + important chemicals and fuels has received considerable attention as an emerging technology. Since CO₂ is thermodynamically stable and kinetically inert, the effective activation of CO₂ molecule for the selective transformation to target products still remains a challenge. The well-designed CO₂ reduction route and efficient catalyst system has imposed the feasibility of CO₂ conversion into C_2 + chemicals and fuels. In this paper, we have reviewed the recent advances on chemical conversion of CO₂ into C_2 + chemicals and fuels with wide practical applications, including important alcohols, acetic acid, dimethyl ether, olefins and gasoline. In particular, the synthetic routes for CC coupling and carbon chain growth, multifunctional catalyst design and reaction mechanisms are exclusively emphasized.     

The comparison study on the operating condition of gasification power plant with various feedstocks

Gasification technology, which converts fossil fuels into either combustible gas or synthesis gas (syngas) for subsequent utilization, offers the potential of both clean power and chemicals. Especially, IGCC is recognized as next power generation technology which can replace conventional coal power plants in the near future. It produces not only power but also chemical energy sources such as H₂, DME and other chemicals with simultaneous reduction of CO₂. This study is focused on the determination of operating conditions for a 300 MW scale IGCC plant with various feedstocks through ASPEN plus simulator. The input materials of gasification are chosen as 4 representative cases of pulverized dry coal (Illinois#6), coal water slurry, bunker-C and naphtha. The gasifier model reflects on the reactivity among the components of syngas in the gasification process through the comparison of syngas composition from a real gasifier. For evaluating the performance of a gasification plant from developed models, simulation results were compared with a real commercial plant through approximation of relative error between real operating data and simulation results. The results were then checked for operating characteristics of each unit process such as gasification, ash removal, acid gas (CO₂, H₂S) removal and power islands. To evaluate the performance of the developed model, evaluated parameters are chosen as cold gas efficiency and carbon conversion for the gasifier, power output and efficiency of combined cycle. According to simulation results, pulverized dry coal which has 40.93% of plant net efficiency has relatively superiority over the other cases such as 33.45% of coal water slurry, 35.43% of bunker-C and 30.81% of naphtha for generating power in the range of equivalent 300 MW.     

Fuels and Energy for the Future: The Role of Catalysis

Abstract

There are many reasons to decrease the dependency on oil and to increase the use of other energy sources than fossil fuels. The wish for energy security is balanced by a wish for sustainable growth. Catalysis plays an important role in creating new routes and flexibility in the network of energy sources, energy carriers, and energy conversion. The process technologies resemble those applied in the large scale manufacture of commodities. This is illustrated by examples from refinery fuels, synfuels, and hydrogen and the future role of fossil fuels is discussed.     

The fate of main gaseous and nitrogen species during fast heating rate devolatilization of coal and secondary fuels using a heated wire mesh reactor

Fast devolatilization experiments of coal and biomass fuels have been carried out using a heated wire mesh setup integrated within an FTIR spectrophotometer for in-situ gas analysis. A bituminous coal and slaughter/poultry biomass residues, currently utilized in the Dutch power sector as secondary fuels in coal-fired utilities, have been studied. The influence of peak temperature (500–1300 °C), heating rate (600–1000 K/s) and hold time at peak temperature on the devolatilization has been investigated. Particular emphasis was given to characterize the fuel-bound nitrogen partitioning of these fuels as a function of the various operating parameters. The results suggest that, for combustion applications, the effectiveness of primary measures for NO_x control can be enhanced when biomass fuels are co-fired with coal if a complete devolatilization is ensured in the fuel-rich zone of the furnace.     

煤直接转化制高品质液体燃料和化学品

介绍了国家重点研发计划项目“低变质煤直接转化制高品质液体燃料和化学品的基础研究”的背景、研究现状以及研究任务与目标。研究工作可望在深入认识低变质煤中矿物特性和弱键合结构以及分子水平反应规律、直接转化过程反应途径、产物调控机制及定向催化转化原理;构建高品质和高产率油气的煤热解新反应器、煤加氢液化富产芳烃新工艺、高性能喷气燃料及化学品制备的高效催化剂以及新技术等方面取得突破,从而完善低变质煤直接转化制取高品质液体燃料及化学品的工艺技术体系。     

Co-gasification of coal and wood in a dual fluidized bed gasifier

In the last decade the reduction of CO₂ emissions from fossil fuels became a worldwide topic. Co-gasification of coal and wood provides an opportunity to combine the advantages of the well-researched usage of fossil fuels such as coal with CO₂-neutral biomass. Gasification itself is a technology with many advantages. The producer gas can be used in many ways; for electric power generation in a gas engine or gas turbine, for Fischer-Tropsch synthesis of liquid fuels and also for production of gaseous products such as synthetic natural gas (bio SNG). Moreover, the use of the producer gas in fuel cells is under investigation. The mixture of coal and wood leads to the opportunity to choose the gas composition as best befits the desired process. Within this study the focus of investigation was of gasification of coal and wood in various ratios and the resulting changes in producer gas composition. Co-gasification of coal and wood leads to linear producer gas composition changes with linear changing load ratios (coal/wood). Hydrogen concentrations rise with increasing coal ratio, while CO concentrations decrease. Due to the lower sulfur and nitrogen content of wood, levels of the impurities NH₃ and H₂S in the producer gas fall with decreasing coal ratio. It is also shown that the majority of sulfur is released in the gasification zone and, therefore, no further cleaning of the flue gas is necessary. All mixture ratios, from 100 energy% to 0 energy% coal, performed well in the 100 kW dual fluidized bed gasifier. Although the gasifier was originally designed for wood, an addition of coal as fuel in industrial sized plants based on the same technology should pose no problems.     

Use of carbon dioxide as feedstock for chemicals and fuels: homogeneous and heterogeneous catalysis

CO₂ is considered to play a key role in an eventual climate change, due to its accumulation in the atmosphere. The control of its emission represents a challenging task that requires new ideas and new technologies. The use of perennial energy sources and renewable fuels instead of fossil fuels and the conversion of CO₂ into useful products are receiving increased attention. The utilization of CO₂ as a raw material for the synthesis of chemicals and fuels is an area in which scientists and industrialists are much involved: the implementation of such technology on a large scale would allow a change from a linear use of fossil carbon to its cyclic use, mimicking Nature. In this paper the use of CO₂ as building block is discussed. CO₂ can replace toxic species such as phosgene in low energy processes, or can be used as source of carbon for the synthesis of energy products. The reactions with dihydrogen, alcohols, epoxides, amines, olefins, dienes, and other unsaturated hydrocarbons are discussed, under various reaction conditions, using metal systems or enzymes as catalysts. The formation of products such as formic acid and its esters, formamides, methanol, dimethyl carbonate, alkylene carbonates, carbamic acid esters, lactones, carboxylic acids, and polycarbonates, is described . The factors that have limited so far the conversion of large volumes of CO₂ are analyzed and options for large‐scale CO₂ catalytic conversion into chemicals and fuels are discussed. Both homogeneous and heterogeneous catalysts are considered and the pros and cons of their use highlighted. © 2013 Society of Chemical Industry     

Catalytic hydrogenation of coal to value added chemicals

The present as well as future shortages of petroleum derived hydrocarbons for use as starting materials for the synthesis of various organic chemicals and products have stimulated search in the use of Coal/Lignite as raw materials for chemicals production. Coal can be exploited to produce carbocyclic derivatives for a wide spectrum of commercial applications in the field of polymers, dyes and drugs. In the present study catalytic coal hydrogenation under milder conditions (reaction temperature 180–200°C, reaction pressure 18–20 kg/cm³ the coal molecule may break into smaller fragments, i.e., smaller aromatic units with different functional groups. These aromatic chemicals are important for making different value added products.     

Reactions of synthesis gas

The use of synthesis gas (syngas) offers the opportunity to furnish a broad range of environmentally clean fuels and chemicals. There has been steady growth in the traditional uses of syngas. Almost all hydrogen gas is manufactured from syngas and there has been a tremendous spurt in the demand for this basic chemical; indeed, the chief use of syngas is in the manufacture of hydrogen for a growing number of purposes. Methanol not only remains the second largest consumer of syngas but has shown remarkable growth as part of the methyl ethers used as octane enhancers in automotive fuels. The Fischer-Tropsch synthesis remains the third largest consumer of syngas, mostly for transportation fuels but also as a growing feedstock source for the manufacture of chemicals, including polymers. Future growth in Fischer-Tropsch synthesis may take place outside the continental United States. The hydroformylation of olefins (the oxo reaction), a completely chemical use of syngas, is the fourth largest use of carbon monoxide and hydrogen mixtures; research and industrial application in this field continue to grow steadily. A direct application of syngas as fuel (and eventually also for chemicals) that promises to increase is its use for Integrated Gasification Combined Cycle (IGCC) units for the generation of electricity (and also chemicals) from coal, petroleum coke or heavy residuals. In the period 2005–2015, the amount of syngas employed in this manner may approach that used for all other specific purposes. Syngas is the principal source of carbon monoxide, which is used in an expanding list of so-called carbonylation reactions.     

Liquid Fuels from Alternative Carbon Sources Minimizing Carbon Dioxide Emissions

The energy needs of the world continue to grow, as does the resulting environmental impact. Policy makers continue to call for alternative energies to replace today's petroleum‐based liquid fuels. However, liquid fuels have significant advantages, and it is probably unwise to abandon the existing infrastructure without appropriately exploring alternatives to lessen the environmental burden of producing liquid fuels. Biomass and coal are often proposed as alternatives to petroleum‐based carbon sources, but those processes lose a significant amount of their potential product to unwanted carbon dioxide emissions. However, combining biomass and coal with cleaner natural gas yields processes with less environmental impact to produce liquid fuels with small, zero, or even negative carbon dioxide emissions. Our process synthesis approach is applied to commonly encountered liquid fuel production methods to identify promising routes and to establish feasibility limits on those less promising alternatives. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2062–2078, 2013     

煤间接液化技术及其发展状况

介绍了煤间接液化技术的特点,从其原理、工艺路线、关键技术及发展现状等方面对间接液化技术进行了详细的阐述,指出发展煤间接液化是解决我国油品短缺的根本途径。     

Geometrical Theory of Heterogeneous Catalysis and the Role of Tunneling Therein

Abstract

The utilization of petroleum is managed primarily by heterogeneous catalysis. This technology at least quadruples the usefulness of a given amount of crude oil as compared to thermal processing. It seems clear that a similar increase in the usefulness of other fossil fuels such as coal and oil shale should be possible, In view of the energy shortage which we have all come to realize in the last year or so, the important central role of heterogeneous catalysis seems to be obvious.     

Peach and apricot stone combustion in a bubbling fluidized bed

In this study, a bubbling fluidized bed combustor (BFBC) of 102 mm inside diameter and 900 mm height was used to investigate the combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry. A lignite coal was also burned in the same combustor. The combustion characteristics of the wastes were compared with that of a lignite coal that is most widely used in Turkey. On-line concentrations of O₂, CO, CO₂, SO₂, NO_X and total hydrocarbons (C_mH_n) were measured in the flue gas during combustion experiments. By changing the operating parameters (excess air ratio, fluidization velocity, and fuel feed rate), the variation of emissions of various pollutants was studied. Temperature distribution along the bed was measured with thermocouples.During the combustion tests, it was observed that the volatile matter from peach and apricot stones quickly volatilizes and mostly burn in the freeboard. The temperature profiles along the bed and the freeboard also confirmed this phenomenon. It was found that as the volatile matter of fruit stones increases, the combustion takes place more in the freeboard region.The results of this study have shown that the combustion efficiencies ranged between 98.8% and 99.1% for coal, 96.0% and 97.5% for peach stone and 93.4% and 96.3% for apricot stones. The coal has zero CO emission, but biomass fuels have very high CO emission which indicates that a secondary air addition is required for the system. SO₂ emission of the coal is around 2400–2800 mg/Nm³, whereas the biomass fuels have zero SO₂ emission. NO_X emissions are all below the limits set by the Turkish Air Quality Control Regulation of 1986 (TAQCR) for all tests. As the results of combustion of two biomass fuels are compared with each other, peach stones gave lower CO and NO_X emissions but the SO₂ emissions are a little higher than for apricot stones. These results suggest that peach and apricot stones are potential fuels that can be utilized for clean energy production in small-scale fruit juice industries by using BFBC.     

The Application of Zeolites and Periodic Mesoporous Silicas in the Catalytic Conversion of Synthesis Gas

In the recent years there has been a rising interest in the conversion of remote and abundant natural gas as well as renewable biomass sources into high quality fuels and valuable raw chemicals via synthesis gas (syngas, CO + H₂) as a versatile intermediate. The metal catalysed CO hydrogenation can be selectively directed towards hydrocarbons as precursors of ultra clean liquid fuels (Fischer-Tropsch synthesis) or to added-value products such as light olefins and oxygenates (alcohols, carboxylic acids, ethers, etc.). By taking advantage of their unique and tunable structural and chemical properties, inorganic molecular sieves such as zeolites and periodic mesoporous silicas have been extensively explored as effective components of heterogeneous catalysts for the selective conversion of syngas. Thus, ordered mesoporous silicas (MCM-41, MCM-48, SBA-15) have shown interesting properties as catalytic supports for Co and Fe based Fischer-Tropsch catalysts. Besides, zeolite-entrapped mono and bimetallic clusters have been reported to selectively direct the synthesis towards oxygenates. In this work, the use of the original structural properties of these materials to tailor the dispersion, geometrical location and chemical state of metallic sites leading to heterogeneous catalysts with enhanced activity and selectivity in syngas catalytic routes is reviewed. The introduced peculiarities, benefits and drawbacks of these structured solids in comparison to conventional amorphous supports are also discussed.     

Technology of the Fischer-Tropsch Process

Abstract

Sasol One, formerly known as South African Coal, Oil, and Gas Corp., operates a plant for the production of liquid fuels, pipeline gas, and chemical products from coal in Sasolburg in the province of the Orange Free State in South Africa. This plant started production in 1955 and today Sasol has 25 years' practical experience with the production of synthesis gas via Lurgi coal gasification and the synthesis of hydrocarbons by the Fischer-Tropsch process. In 1975 the decision was taken to build a much larger Fischer-Tropsch plant, mainly for the production of motor fuels, and this plant is at present being commissioned. The first final products from this plant will become available to the public early in the second half of 1980. The continuing increase in crude oil prices and instability on the oil supply market were the incentives for the decision in 1979 to build anther Sasol plant practically identical to Sasol Two. Construction on this Sasol Three plant is well under way and it is expected to start producing in 1982. The three plants together will bring South Africa significantly closer to its goal of independence from foreign crude oil supplies.     

The Application of High Field and High Gradient Methods to the Magnetic Separation of Mineral Matter from Micronized Coal

Abstract

In exploratory laboratory measurements, high field high gradient magnetic separation (HGMS) has removed as much as 74% of the mineral matter and 99% of the pyritic sulfur from micronized coals with mineral contents up to 16.39 wt%. Magnetic cleaning methods are limited by the fact that not all mineral matter in coal is magnetic. HGMS methods are further restricted when mineral matter levels generally exceed about 2 to 3% because of excessive capture-matrix loading which leads to poor clean coal weight yields. The use of selective flocculation of coal mineral matter and processing at high flow velocities (made possible with the use of high field superconductive magnet technology) offer hope for overcoming these process limitations and for extending use of HGMS technology to preparation of low ash and low sulfur coal-slurry fuels. Measurements of mineral matter and sulfur removals achieved in high field HGMS processing of water slurries of dispersed micronized coals are presented. Field strengths up to 15 Tesla, flow velocities up to 3 cm/s, and slurry solids up to 38.4% were investigated. The use of models of the magnetic capture mechanism for scaling laboratory data to commercial applications is discussed.     

Effects of Dilution Sampling on Fine Particle Emissions from Pulverized Coal Combustion

A dilution sampler was used to examine the effects of dilution ratio and residence time on fine-particle emissions from a pilot-scale pulverized coal combustor. Measurements include the particle size distribution from 0.003 to 2.5 μm, PM_2.5 mass, and PM_2.5 composition (OC/EC, major ions, and elemental). Heated filter samples were also collected simultaneously at stack temperatures in order to compare the dilution sampler measurements with standard stack sampling methodologies. Measurements were made both before and after the bag house, the particle control device used on the coal combustor, and while firing three different coal types and one coal–biomass blend. The PM_2.5 mass emission rates measured using the dilution sampler agreed to within experimental uncertainty with those measured with the hot-filter sampler. Relative to the heated filter sample, dilution did increase the PM_2.5 mass fraction of selenium for all fuels tested, as well as ammonium and sulfate for selected fuels. However, the additional particulate mass created by gas-to-particle conversion of these species is within the uncertainty of the gravimetric analysis used to determine the overall mass emission rate. The enrichment of PM_2.5 selenium caused by dilution did not vary with dilution ratio and residence time. The enrichment of PM_2.5 sulfate and ammonium varied with fuel composition and dilution ratio but not residence time. For example, ammonium was only enriched in diluted acidic aerosol samples. A comparison of the PM_2.5 emission profiles for each of the fuels tested underscores how differences in PM_2.5 composition are related to the fuel ash composition. When sampling after the bag house, the particle size distribution and total particle number emission rate did not depend on residence time and dilution ratio because of the much lower particle number concentrations in diluted sample and the absence of nucleation. These results provide new insight into the effects of dilution sampling on measurements of fine particle emissions, providing important data for the ongoing effort of the EPA and ASTM to define a standardized dilution sampling methodology for characterizing emissions from stationary combustion sources.