Methane to higher hydrocarbons via halogenation

Activation of methane with a halogen followed by the metathesis of methyl halide is a novel route from methane to higher hydrocarbons or oxygenates. Thermodynamic analysis revealed that bromine is the most suitable halogen for this goal. Analysis of the published data on the reaction kinetics in a CSTR enabled us to judge on the effects of temperature, reactor residence time and the feed concentrations of bromine and methane to the conversion of methane and the selectivity towards mono or dibromomethane. The analysis indicated that high dibromomethane selectivity is attainable (over 90%) accompanied by high methane conversions. The metathesis of dibromomethane can provide an alternative route to the conversion of methane (natural gas) economically with smaller installations than the current syn-gas route.     

烃类在超临界水中的化学转化

超临界水是一种新型反应介质,烃类在超临界水中化学转化效率高。对烃类在超临界水反应制氢气、重油改质和合成含氧化合物方面的研究进展进行了综述,同时简要介绍了各种技术产生的背景,对研究重点进行了必要评述,展望了该领域的发展前景。     

A direct catalytic conversion of natural gas to C2+ hydrocarbons by microwave plasma

Methane, the major constituent of natural gas, was converted to higher hydrocarbons by a microwave plasma. The yield of C2+ products increased from 29.2 % to 42.2% with increasing plasma power and decreasing flow rate of methane. When catalysts were used in the plasma reactor, the selectivities of ethylene and acetylene increased, while the yield of C2+ remained constant. Among various catalysts used, Fe catalyst showed the highest ethylene selectivity of 30 %. And when the actual natural gas was introduced, more C2+ products were obtained (46%). This is due to the ethane and propane in the natural gas. Applying electric field inductance for evolving the high plasma, we obtained high C2+ products of 63.7 % when Pd-Ni bimetal catalyst was used.     

Low-temperature synthesis of graphene on Cu using plasma-assisted thermal chemical vapor deposition

Plasma-assisted thermal chemical vapor deposition (CVD) was carried out to synthesize high-quality graphene film at a low temperature of 600°C. Monolayer graphene films were thus synthesized on Cu foil using various ratios of hydrogen and methane in a gaseous mixture. The in situ plasma emission spectrum was measured to elucidate the mechanism of graphene growth in a plasma-assisted thermal CVD system. According to this process, a distance must be maintained between the plasma initial stage and the deposition stage to allow the plasma to diffuse to the substrate. Raman spectra revealed that a higher hydrogen concentration promoted the synthesis of a high-quality graphene film. The results demonstrate that plasma-assisted thermal CVD is a low-cost and effective way to synthesis high-quality graphene films at low temperature for graphene-based applications.     

Direct conversion of synthesis gas to aromatic hydrocarbons: Variation of product distribution with time-on-stream

The synthesis of hydrocarbons from syngas was studied over a zirconia-based cobalt-nickel catalyst (FT catalyst) alone as well as mixed with zeolite HZSM-5 at 101.3 kPa in a 12.7 mm i.d. down flow reactor. The product distribution was recorded as a function of time-on-stream for several days of continuous operation under fixed operating conditions of 250°C and H₂/CO = 1. For the FT + HZSM-5 system, a dramatic variation in the product distribution takes place during the first 24 h of operation. A comparison of time-on-stream results obtained using FT catalyst alone and mixed with HZSM-5 suggests that the reactions leading to the build-up of overall product distribution are slower over HZSM-5 compared to those taking place over FT catalyst. These differences have been attributed to the different nature of reactions taking place over the two components of the mixed catalyst system. Analyses of the coke on the deactivated catalysts are also reported.     

Non-catalytic conversion of wheat straw,walnut shell and almond shell into hydrogen rich gas in supercritical water media

Agricultural wastes as lignocellulosic biomasses are known as the major resources of bioenergy. These valuable resources can be converted into useful environmental friendly fuels and chemicals. Wheat straw, walnut shell and almond shell are the main agricultural wastes in Kurdistan province, Iran. This study investigates the hydrogen-rich gas production via gasification of these biomasses in supercritical water media. Experiments were performed first, in the base case condition using a stainless steel batch micro reactor system. Then, the effect of reaction time on the total gas yield and yield of hydrogen, were investigated. It was seen that the total gas yields and gasification efficiencies increased by increasing the reaction time to 30 min and then the total gas yield was approximately remained constant. Among three used feed stocks, wheat straw with higher amount of cellulose and lower amount of lignin had the highest total gas and hydrogen yields in shorter reaction times. The maximum hydrogen yields of 7.25, 4.1 and 4.63 mmol per gram of wheat straw, almond shell and walnut shell occurred at 10, 15 and 20 min of reaction time, respectively.     

A kinetic study on the conversion of methane to higher hydrocarbons in a radio-frequency discharge

This study investigated methane conversion with direct current discharge at low pressure in a radio frequency. The main gaseous products of the reaction were ethane, ethylene, acetylene and propane. This study was concentrated on the influence of discharge conditions on the conversion of methane to higher hydrocarbons. Reaction temperature, electron density and mean residence time were calculated from experimental data and mathematical relations. The maximum conversion of the methane was about 45% with the pure methane as a reactant. Ethane was the main product when the reaction occurred in the glow discharge. Ethane selectivity decreased with the increase of the gas temperature. The kinetics of reactions was also analyzed from possible reaction equations and various rate constant data. Consequently, the dissociation constant and the density of radicals could be obtained at any experimental conditions.     

Biological conversion of coal and coal-derived synthesis gas

Recent research has resulted in a number of promising biological pathways to produce clean fuels from coal. These processes all involve two or more steps: either the biosolubilization of coal, followed by bioconversion to ethanol or methane; or conversion of coal to synthesis gas, followed by bioconversion into alcohols or methane. Sulfur may also be removed from the solubilized coal or synthesis gas in a separate, or concurrent, biological step. This paper presents research results from both the direct and indirect conversion of coal to liquid fuels using biological processes. A review of direct conversion techniques in producing liquid fuels from coal in a serial conversion process is presented. In addition, bioreactor design data for the conversion of CO, CO₂ and H₂ in synthesis gas by Clostridium ljungdahlii in both batch and continuous culture are reviewed and discussed.     

Catalytic conversion of Euphorbia neriifolia biocrude into petroleum hydrocarbons

The latex of Euphorbia neriifolia has been studied with a view to its development as a potential petrocrop. Hydrocracking of biocrude afforded 72% conversion to products (C₅ and larger molecules), comprising up to 35% gasoline (b.p. 65–150 °C) and 15% kerosene (150–260 °C) in addition to other products. About 70% of the hydrocarbon material present in the gasoline fraction has been characterized.     

Catalysts in the conversion of coal and shale into synthetic hydrocarbons

The preparation and use of Co catalysts for the synthesis of hydrocarbons from CO and H₂ mixtures—coal and oil shale gasification products—were considered. Problems related to increasing the activity and selectivity of the catalytic test systems were reported.     

Kinetic modelling of the catalytic conversion of synthesis gas

A kinetic study for the one-step conversion of synthesis gas to gasoline on a ZnO–Cr₂O₃–ZSM-5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr₂O₃ component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well-mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO₂ was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.     

混合制冷剂中重烃对天然气液化流程的影响

混合制冷剂(MR)组分是影响天然气液化流程性能的最重要因素之一。在某些特定的液化天然气(LNG)装置中,丁烷和戊烷等重组分不受欢迎。研究了以下4种混合制冷剂组分用于单混合制冷剂(SMR)流程的效果:含有异丁烷(C₄)和异戊烷(C₅)的MR;不含C₄的MR;不含C₅的MR;不含C₄和C₅的MR。对各流程的比功耗进行了对比。结果表明,相比于异丁烷,异戊烷对降低能耗的贡献更大;另外,工况1的能耗比工况4低18%。更进一步地,提出了采用不同制冷剂进行预冷的SMR流程。对于工况4,采用丙烷预冷的流程能耗可降低12%。     

An investigation into the conversion of methanol to hydrocarbons over a SAPO-34 catalyst using magic-angle-spinning NMR and gas chromatography

¹³C magic-angle-spinning (MAS) NMR, along with the results of Fourier transform infrared and gas chromatographic analysis, has been used to identify the hydrocarbon products, and to distinguish mobile from static species, formed from methanol within the pores of a H-SAPO-34 catalyst. The reasons for the differences in product distribution within the pores (monitored by MAS NMR) and in the gas phase (monitored chromatographically) are discussed.     

The conversion of waste polystyrene into useful hydrocarbons by microwave-metal interaction pyrolysis

Waste polystyrene was pyrolyzed at temperatures as high as the melting point of aluminum into styrene and other substituted aromatic compounds. This temperature was attained by the interaction of microwaves with aluminum in the form of a tightly coiled wire, strips, and cylinder. The rate of reaction was found to depend on the size, shape and form. The reaction was faster for the coil, slower for strips and negligible for the cylindrical form. The yields of pyrolysis were also found to depend on size, shape and form of the metal. The products of the pyrolysis were found to contain 88 wt % liquid, 9-10 wt % gases and residual char. The liquid portion was collected using cold traps and measured, whereas the amount of gas was obtained by taking difference. The liquid portion was analyzed using GC/MS and found that it contains substituted benzene in addition to polycyclic aromatics and condensed ring aromatics. The gases were identified using acetylide formation and Baeyer's test. The products, formation, mechanism of the reaction, and nature of products are discussed.     

One-stage catalytic conversion of natural gas into liquid products

Galloaluminosilicates with silica ratios from 30 to 80 containing different gallium oxide proportions ([Ga₂O₃] = 1.2 and 2.2 wt %) have been prepared by hydrothermal synthesis. The activity and selectivity of the catalysis in the conversion of natural gas to aromatic hydrocarbons have been studied.     

Research activities and recent progresses on synthesis gas conversion

Five catalytic processes and their catalysts will be introduced in my talk. Firstly,the demonstration test(3000 ton/a)results using a novel catalyst Co/SiO2 with egg-shell structure and the strategies for this catalyst preparation based on the issues from the mass transfer of produced wax from F-T synthesis will be discussed. Recent progresses on C2-oxygenate synthesis from syngas over a Rh/SiO2 catalyst and a 10 thousands ton/a demonstration test facility in China will be built in 2010 will be reported in the second section. A naphtha and diesel distillate which cut off the heavier end of S-F-A distribution direct synthesis with low methane selectivity from syngas over a Co/AC1 catalyst and a 10000 ton/a demonstration test with a bubble column slurry reactor will be talked about in this speech. A high α-alcohols of C2-C18 direct synthesis with more than 50 wt% selectivity and low methane and methanol selectivities from syngas over a Co2C/AC2 catalyst,a 3000 ton/a demonstration test with a bubble column slurry reactor and the primary fundamental understandings will be detailedly discussed in the forth section. In situ formation of homogeneous active sites on the surface of supported Rh heterogeneous catalysts and their application in hydroformylation of olefins will be introduced in fifth section.     

抽氢气及合成气工艺在合成氨装置的应用

介绍了抽氢气、合成气装置的工艺路线,技术特点,运行情况。该工艺在30万t／a年合成氨装置上的应用为国内首创,7．0MPa甲烷化工艺的工业化应用亦为国内首创。     

High yields of synthesis gas by millisecond partial oxidation of higher hydrocarbons

Cyclohexane, n-hexane, and isooctane were reacted with air in a Rh-monolith reactor and converted into synthesis gas (H₂+CO) in yields exceeding 90%, with >95% conversion of fuels and 100% conversion of oxygen. The best catalyst was an 80 ppi washcoated alumina monolith containing 5 wt% Rh. There was a small effect of catalyst contact time on syngas selectivity and conversions for gas space velocities from 3×10⁵ to 3×10⁶ h^–1. Preheating the feed enhances syngas selectivities slightly, but no reactor preheat is necessary provided the fuel remains vaporized. Addition of 25 mol% toluene to isooctane also produces syngas, olefins, and methane with 90% yield, including 70% yield to syngas. Partial oxidation of gasoline–air mixtures was attempted but the catalysts were poisoned after several hours, probably by sulfur and/or metals.