An anodic alumina supported Ni–Pt bimetallic plate-type catalysts for multi-reforming of methane,kerosene and ethanol

An anodic alumina supported Ni–Pt bimetallic plate-type catalyst was prepared by a two-step impregnation method. The trace amount 0.08 wt% of Pt doping efficiently suppressed the nickel particle sintering and improved the nickel oxides reducibility. The prepared Ni–Pt catalyst showed excellent performance during steam reforming of methane, kerosene and ethanol under both 3000 h stationary and 500-time daily start-up and shut-down operation modes. Self-activation ability of this catalyst was evidenced, which was considered to be resulted from the hydrogen spillover effect over Ni–Pt alloy. In addition, an integrated combustion-reforming reactor was proposed in this study. However, the sintering of the alumina support is still a critical issue for the industrialization of Ni–Pt catalyst.     

Development and evaluation of a microreactor for the reforming of diesel fuel in the kW range

The development and evaluation of a reactor based on microchannel technology for the reforming of diesel fuel is reported. The reactor itself was based on an integrated reformer/burner heat exchange reactor concept. 38 h of diesel reforming was performed at temperatures above 750 °C and at various S/C ratios, down to a minimum of 3.17, up to an electrical power equivalent of 5 kW. Over 98% total diesel conversion was observed at all times over the testing period. Variation of experimental parameters such as O/C and S/C ratios are critical for optimum operation of the reformer.     

Ammonia as hydrogen carrier for transportation; investigation of the ammonia exhaust gas fuel reforming

In this paper we show, for the first time, the feasibility of ammonia exhaust gas reforming as a strategy for hydrogen production used in transportation. The application of the reforming process and the impact of the product on diesel combustion and emissions were evaluated. The research was started with an initial study of ammonia autothermal reforming (NH₃ – ATR) that combined selective oxidation of ammonia (into nitrogen and water) and ammonia thermal decomposition over a ruthenium catalyst using air as the oxygen source. The air was later replaced by real diesel engine exhaust gas to provide the oxygen needed for the exothermic reactions to raise the temperature and promote the NH₃ decomposition. The main parameters varied in the reforming experiments are O₂/NH₃ ratios, NH₃ concentration in feed gas and gas – hourly – space – velocity (GHSV). The O₂/NH₃ ratio and NH₃ concentration were the key factors that dominated both the hydrogen production and the reforming process efficiencies: by applying an O₂/NH₃ ratio ranged from 0.04 to 0.175, 2.5–3.2 l/min of gaseous H₂ production was achieved using a fixed NH₃ feed flow of 3 l/min. The reforming reactor products at different concentrations (H₂ and unconverted NH₃) were then added into a diesel engine intake. The addition of considerably small amount of carbon – free reformate, i.e. represented by 5% of primary diesel replacement, reduced quite effectively the engine carbon emissions including CO₂, CO and total hydrocarbons.     

Effect of excess oxygen in plasma reforming of diesel fuel

This study investigated the plasma reforming process for diesel focusing on the relative ratio of oxygen to fuel. Excess O₂ in the partial oxidation process is known to increase the combustion portion, resulting in a decreased yield of H₂ and CO. However, in this parametric investigation, there was no apparent decrease in the H₂ and CO selectivity. Adding O₂ did not increase the portion of combustion in the overall reaction. Rather, an excess O₂ supply from partial oxidation stoichiometry resulted in an increase in CO₂ selectivity without a reduction in CO selectivity. Heavy hydrocarbon species were identified as a source of CO₂ in excess O₂ conditions due to preferential oxidative cracking. The additional oxidation of C₁–C₄ species by excess O₂ provided a minor contribution to CO₂. Excess O₂ affects soot generation characteristics by suppressing the agglomeration of soot particles, resulting in smaller particle generation. However, the oxidation of soot particles does not provide a major contribution to increasing the CO₂ selectivity. The results show that in a real reforming process, controlling the O₂ supply does not have a strong effect on the process selectivity of hydrogen.     

Spraying of liquid fuel for improvement of reforming performance for hydrogen generation

In the present study, the effects of spraying conditions on reforming performance were investigated experimentally. Kerosene was used as the liquid fuel for reforming and sprayed by a twin fluid nozzle to facilitate uniform mixing with air and water (steam) at the downstream. The separate effects of the mean drop size of the fuel, the position of the catalytic bed and the air flow rate on the reforming efficiency were analyzed, and the reasons for the results were discussed by examining the temperature distribution inside the reformer and also through visualization of the catalytic bed during the reforming process. The overall reforming efficiency was significantly improved by spraying the fuel because the mixing between the reactants was enhanced. When the distance from the nozzle to the catalytic bed became closer, higher reforming performance was achieved with larger fuel drops due to the more rapid penetration into the catalytic bed with larger momentum. With a larger amount of air supply to the system, fuel reformation was promoted by the high reaction temperature. On the other hand, with the longer distance between the nozzle and the catalytic bed, the poor mixing between the fuel and other reactants (due to the side-wall collision of fuel drops and possible formation of liquid film along the wall) predominated over other effects, and the drop size effect was not accordingly observed.     

重油预混层流点火特性的仿真分析

基于重油点火特性研究的需要,利用定容燃烧弹研究预混层流燃烧的优点,采用仿真分析方法对定容燃烧弹中柴油和煤油混合气预混层流点火特性进行了研究,得出了柴油和煤油的点火特性;研究成果可为重油发动机的开发提供一定的理论参考。     

Spray formation of middle distillates for autothermal reforming

The reforming of diesel and diesel-like fuels plays a central role in the development of fuel cell systems for on-board power supplies. The vaporization of the fuel via a spray formation and the subsequent mixture with water vapor and air determine the quality of the reforming process, as is shown in this paper. By using a high quality nozzle residual hydrocarbons were below 25 ppmV during the reforming of standard diesel. Through the use of a fuel injector in pulsed operation, the load range was able to be increased from 1:1.67 to 1:6. Spray pattern analyses were conducted using a high-speed camera. The formation of the spray pattern lasted 1.5–2 ms. The testing of a fast-closing magnetic valve manufactured by GSR Ventiltechnik was carried out on the autothermal reformer (ATR) type AH2. It exist not any direct influence of the pulsed operation on hydrogen production.     

Performance improvement of diesel autothermal reformer by applying ultrasonic injector for effective fuel delivery

Technology for the reforming of heavy hydrocarbons, such as diesel, to supply hydrogen for fuel cell applications is very attractive and challenging due to its delicate control requirements. The slow reforming kinetics of aromatics contained in diesel, sulfur poisoning, and severe carbon deposition make it difficult to obtain long-term performance with high reforming efficiency. In addition, diesel has a critical mixing problem due to its high boiling point, which results in a fluctuation of reforming efficiency. An ultrasonic injector (UI) have been devised for effective diesel delivery. The UI can atomize diesel into droplets (∼40 μm) by using a piezoelectric transducer and consumes much less power than a heating-type vapourizer. In addition, reforming efficiencies increase by as much as 20% compared with a non-UI reformer under the same operation conditions. Therefore, it appears that effective fuel delivery is linked to the reforming kinetics on the catalyst surface. A 100-W_e, self-sustaining, diesel autothermal reformer using the UI is designed. In addition, the deactivation process of the catalyst, by carbon deposition, is investigated in detail.     

Long-term stability at fuel processing of diesel and kerosene

The long-term stability at autothermal reforming of diesel fuel and kerosene was studied using Juelich's autothermal reformer ATR 9.2, which is equipped with a commercial proprietary RhPt/Al₂O₃–CeO₂ catalyst. The experiment was run for 10,000 h of time on stream at constant reaction conditions with an O₂/C molar ratio of 0.47, a H₂O/C molar ratio of 1.9, and a gas hourly space velocity of 30,000 h⁻¹. Kerosene produced via the gas-to-liquid process and diesel fuel synthesized via the bio-to-liquid route were used. Both fuels were almost free of mass fractions of sulfur and aromatics. The trends for the desired main products of autothermal reforming H₂, CO, CO₂, and CH₄ were almost stable when kerosene was used. When the fuel mass flow was switched to diesel fuel however, different modes of catalyst deactivation occurred (active sites blocked by carbonaceous deposits, sintering processes), leading to a decrease in the concentrations of H₂ and CO₂ with a simultaneous increase in the CO content. This paper defines carbon conversion as the decisive criterion for evaluating the long-term stability during autothermal reforming of kerosene and diesel fuel. Carbon conversion was diminished via three different pathways during the long-term experiment. Undesired byproducts found in the gas phase leaving the reactor had the strongest impact on carbon conversion. These byproducts included ethene, propene, and benzene. Furthermore, a liquid oily residue was detected floating on the condensed unconverted mass flow of water. This happened once during the whole experiment. Finally, undesired organic byproducts were dissolved in the mass flow of unconverted water. These were found to be straight-chain and branched paraffins, esters, alcohols, acids, aldehydes, ketones, etc. Nevertheless, at the end of the long-term experiment, carbon conversion still amounted to more than 98.2%.     

Static and dynamic modeling of a diesel fuel processing unit for polymer electrolyte fuel cell supply

This article introduces the energetic macroscopic representation (EMR) as approach for the dynamic modeling of a diesel fuel processing unit. The EMR is the first step toward model-based control structure development. The autothermal fuel processing system containing: heat exchanger, reformer, desulfurization, water gas shift, preferential oxidation and condensation is divided into a multitude simple subblocks. Each subblock describes an elementary step of the fuel conversion, several of these blocks may occur in a single module. Calculations are carried out using two basic principles: mass and energy balances. For model-based control development, it is imperative that the model represents dynamic behavior, therefore temperature and pressure dynamics are taken into account in the model. It is shown that the model is capable to predict the stationary behavior of the entire fuel processing unit correctly by comparison with given data. Predictions regarding reformer heat up, temperature and pressure dynamics are also provided.     

Petrol supplies and consumer expectations

A formal model of the consumer's behaviour given uncertain supplies of petrol is developed. The theory derived implies that consumers will attempt to purchase larger quantities than they would under certainty; although, they expect to purchase less. It is shown that a service surcharge will reduce the optimal amount that the consumer attempts to purchase under uncertainty and from this it is concluded that such a fee would save gasoline supplies. Special consideration is given to the role of the consumer's expectations and their revision in this model.     

Shortfall in on-road fuel economy: Implications for public policy

A prime factor in studying energy conservation in the USA has been the improvement in car fuel economy. The Environmental Protection Agency (EPA) has published values for all models for several years. These laboratory values often do not correspond to those found by motorists; the differences, in many cases, between the two sets of data are substantial. Any future policies based on fuel economy will have to take into account the fact that ‘on-road’ values, in miles per gallon, are often much lower than the EPA values. The author devises a simple model to show the likely difference of petrol use in the USA using theoretical and actual fuel economies. This amounts to about 5 000 million gallons between 1976 and 1985, over half of petrol use in 1978.     

Catalysts for H2 production using the ethanol steam reforming (a review)

This review aims to provide an overview of the main catalytic studies of H₂ production by ethanol steam reforming (ESR). The reaction is endothermic and produces H₂, CO₂, CH₄, CO and coke. The conversion and H₂ selectivity of these products depended greatly of the physicochemical properties of the catalysts, active metal, promoters, temperature, long-term reaction, water/ethanol ratio, space velocity, contact time, and presence of O₂. Initial total conversion has been reported in all catalysts evaluated between 300 and 850 °C. The noble catalysts with high selectivity to H₂ (more than 80%) were: Rh, Ru, Pd and Ir and non-noble metal catalysts were: Ni, Co and Cu. The support materials include CeO₂, ZnO, MgO, Al₂O₃, zeolites-Y, TiO₂, SiO₂, La₂O₂CO₃, CeO₂–ZrO₂ and hydrotalcites. The impregnation method produced the best noble metal catalysts in terms of selectivity and conversion. The decrease of coke was related with the presence of basic sites on the support.     

汽油滤清器外壳的炉中钎焊工艺研究

本文介绍了我公司汽油滤清器外壳的气保护炉中钎焊工艺过程及焊后质量检测方法,并分析了钎焊缺陷的产生原因。     

Modelling how much extra motorists pay on the road? A cross-sectional study of profit margins of unleaded petrol in Australia

Gross profitability margin (difference between retail and wholesale prices) for unleaded petrol exhibits substantial variations across 108 cities, towns and regional centres in Australia. This paper examines if such variations (averaged during 2007–2012) can be explained by (a) transport costs proxied by the distance between retailers and wholesalers; (b) the size of the retail market; (c) market competition proxied by the number of cars in the vicinity of the retailers; (d) dummy variables capturing other qualitative attributes associated with the retailers’ locations. Three cross-sectional regressions are estimated but only one successfully passes all diagnostic tests. By identifying a number of locations exhibiting excessive profit margins, the results of this paper enhance the efficiency and transparency of petrol pricing in the retail market. It is found that the extent of excessive profiteering in Western Australia (WA) and South Australia (SA) were lower than other Australian states and territories. This important finding can be explained by a strong presence of independent petrol stations in SA and the successful price-monitoring performance of FuelWatch in WA.     

柴油机喷嘴流动的有限元计算

给出了描述柴油机喷嘴流动的基本方程,对喷嘴端部进行了参数化的网格生成,最后对其进行了有限元计算并给出了一个实例。     

Biogas upgrade to syn-gas (H2-CO) via dry and oxidative reforming

Fuel reforming processes are primarily used to generate hydrogen for fuel cells and in automotive internal combustion engines to improve combustion characteristics and emissions. In this study, biogas is used as the fuel source for the reforming process as it has desirable properties of being both renewable and clean. Two reforming processes (dry reforming and combined dry/oxidative reforming) are studied. Both processes are affected by the gas stream temperature and reactor space velocity with the second process being affected by O₂/CH₄ ratio as well. Our results imply that oxidative reforming is the dominant process at low exhaust temperatures. This provides heat for the dry reforming of biogas and the overall reforming is exothermic. Increase in O₂/CH₄ ratio at low temperature promotes hydrogen production. At high exhaust temperatures (>600 °C), dry reforming of biogas is dominant and the overall reaction is net endothermic.