Diesel

摘要： More stringent environmental legislation imposes severe requirements to reduce the sulfur content in diesel to ultra-low levels with high efficient catalysts.In this paper,a series of CoMo/NDC@alumina catalysts were synthesized by combination of the chemical vapor deposition of nitrogen-doped carbon(NDC)using 1,10-phenanthroline and co-impregnation of Mo and Co active components.The optimal catalyst with additive of 25%1,10-phenanthroline was screened by a series of property characterization and the hydrodesulfrization(HDS)active test.The amount of“CoMoS”active phase of the optimal CoMo/C3 catalyst increased 5.3%as compared with the CoMo/c-Al_(2)O_(3).The introduction of NDC improved the sulfidation degree of Mo by 21.8%as compared to the CoMo/c-Al_(2)O_(3) catalyst,which was beneficial to form more active sites.The HDS conversion of the NDC supported catalysts are higher than CoMo/c-Al_(2)O_(3) whether for the dibenzothiophene(DBT)or 4,6-dimethyl dibenzothiophene(4,6-DMDBT).Further hydroprocessing evaluation with Dagang diesel revealed that the CoMo/C3 catalyst possessed higher HDS property and the removal rate of DBTs in the diesel increased by 4%–11%as compared to the CoMo/c-Al_(2)O_(3) catalyst.

摘要： Exhaust thermal management is essential to allow engines to meet the Euro VI emissions standards and reducing nitrogen oxide emissions is one of the most important targets being pursued nowadays.Along these lines,in the present study,engine’s thermal performances have been evaluated on the basis of a WHTC test,namely a transient engine dynamometer schedule defined by the global technical regulation(GTR)developed by the UN ECE GRPE group(the GTR is covering a world-wide harmonized heavy-duty certification(WHDC)procedure for engine exhaust emissions).The influence of thermal management on fuel consumption,intake,and tailpipe NO_(x) have been quantitatively analyzed for the overrun state.The results have shown that there can be a strong influence on the after-treatment temperatures and tailpipe NO_(x).In particular,the average temperature upstream of the diesel oxidation catalyst(DOC)has been found to increase from 245°C to 254°C,the average temperature of the selective catalytic reduction(SCR)to increase from 248°C to 253°C,the SCR’s minimum temperature to increase from 196°C to 204°C,and the peak value of the NO_(x) emissions in the low-temperature region to decrease from 73 to 51 mg/s.However,the influence of the overrun state’s thermal management strategy on the fuel consumption,the air intake,the ammonia storage,the NO_(2)/NO_(x) ratio,and the urea consumption has been observed to be relatively limited.

摘要： The kinetics of hydrodearomatization (HDA) is studied in an isothermal high-throughput reactor over three catalysts (CoMo, NiMo, and NiMoW) to produce clean diesel fuel according to China’s latest emission standards. The influences of reaction temperature, pressure, the ratio of H2 to oil, and space time were systematically investigated. By analyzing the reaction mechanism, a four-lump kinetic model considering the influence of competitive adsorption was proposed for the hydrodearomatization reaction, and the model parameters were optimized with good fitting. It was found that nitrogen compounds inhibited the hydrodearomatization reaction. The simulation of various catalyst stacking schemes based on the HDA kinetic model is close to the experimental data, proving the reliability of the model. The concentration of aromatic compounds of different loading sequences was predicted with the catalyst gradation model.

摘要： The production and separation of optimal molecules in diesel fuels require a systematic property evaluation for the containing molecules.This paper evaluates the diesel molecules based on four key quality indicators:low-temperature fluidity,cleanliness,ignition,and power performance.We established the corresponding quantitative structure-property relationship models for corresponding properties,which are freezing point,yield sooting index,cetane number,and combustion heat.The models were applied for the screening of the high-performance molecules that is suitable for diesel.The molecular performance distribution of the conventional diesel and biodiesel were also compared.Moreover,we analyzed the effect of different transformation paths on molecular properties,giving guidance on the conversion process design.

摘要： Diesel molecular compositional model has important application for diesel quality prediction,blending,and molecular-level process model development.In this paper,different types of diesel molecular compositional and blending models were constructed based on the SU-BEM framework.More than 1500 representative molecules were selected to form the molecular structure library.The probability density functions(PDFs)combination was determined by experimental data and experience.A quadratic optimization strategy combining genetic algorithm with local optimization algorithm was adopted to improve the accuracy of the compositional model.The model results show good agreement with the experimental data.The diesel blending model was constructed at the molecular-level based on the above diesel compositional models.The properties of the blending model accord with the experimental regulations.It is proved that the compositional models and blending model constructed have high accuracy and strong prediction capability,and are applicable to the industrial process.

摘要： An alternative fuel production was performed by catalytic-pyrolysis of waste tires under a nitrogen (N2) environment and with a zeolite catalyst. Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to removing tire residues from inadequate sites and it can be a sustainable process to produce alternative fuels. The project investigated the conversion of the waste tires into diesel as one way of waste management and also as a viable process which in turn helps to meet the fuel demand. Uses of the diesel and the by-products from the process were also outlined. Experiments were conducted on the pyrolysis process in order to find the optimum conditions for producing the diesel through pyrolysis;the temperature and residence time were optimized in order to get maximum output from the process. The optimum temperature of the reaction was found to be 520˚C and the optimum residence time was 92.5 minutes. Quality tests of the product were then conducted on the obtained product and most of the properties were found to meet the required standard specifications. The most critical properties which are density, final boiling point, flash point and kinematic viscosity, were found to be 0.8495 g/cm3, 370˚C, 50.5˚C and 3.681 cSt, respectively, and they were within the required specifications. Quality analysis showed that a quality product that is suitable for automobiles could be obtained from the process. The process also produces useful by-products such as char, which can aid in the purification process of the diesel after conversion to activated carbon. The process is environmentally friendly if the appropriate pollution prevention methods like gas absorption are thoroughly implemented. Waste tires are an alternative source of diesel and hence the feasibility of implementing the project on a large scale.

摘要： The internal combustion engines can remain the advantage over competitor technologies for automotive driven,especially the engine efficiency,exceeded 50%while maintaining ultra-low emissions.In this paper,a novel combustion mode characterized by dual high-pressure common-rail direct injection systems,denoted as intelligent charge compression ignition(ICCI)combustion,is proposed to realize high efficiency and clean combustion in wide engine operating ranges.Specifically,commercial gasoline and diesel,which are considered to be complementary in physical and chemical properties,are directly injected into the cylinder by the two independent injection systems,respectively.Through this unique design,the in-cylinder air-fuel mixtures can be flexibly adjusted by regulating injection timing and duration of different fuels,consequently obtaining suitable combustion phase and heat release rate.The ICCI mode can widely run from indicated mean effective pressure 2 bar to 16 bar with an utterly controllable cylinder pressure rising rate,around 50%indicated thermal efficiency and low NOxemissions.A series of experiments were carried out to compare the combustion and emissions of ICCI with other combustion modes(including conventional diesel combustion,reactivity-controlled compression ignition,partially premixed combustion,and gasoline compression ignition).The results show that at the medium engine loads,ICCI mode can reach much high indicated thermal efficiency,especially up to 52%along with extremely low NOxemissions.Prospectively,ICCI mode can realize real-time adjustments of in-cylinder mixture stratification and instantaneous combustion mode switch in one cycle at any operating conditions,and has an excellent commercial application prospect for energy conservation and environmental improvement.

摘要： Dear editor,Diesel engines have been widely used in vehicles because of their excellent fuel efficiency and durability. Although they only represent a small percentage of vehicle ownership, they cause the majority of on-road emissions such as NOx and PM [1].

摘要： The use of ethanol is a promising method to reduce the emissions of diesel engines.The present study has been based on the installation of a gasoline electronic injection system in a single-cylinder diesel engine to control the amount of ethanol entering the cylinder during the compression(while diesel has been injected into the cylinder by the original pump injection system).The injection time has been controlled by crank angle signal collected by an AVL angle indicator.In the tests ethanol and diesel each accounted for half of the fuel volume,and the total heat energy supply of the fuel was equivalent to that of the diesel under the operating conditions of the original engine.A three-dimensional combustion model of the diesel engine has been implemented by using the CFD software FIRE.Simulations have been carried out assuming uniform and non-uniform injections rate for the different holes and the different results have been compared.According to these results,a non-uniform injection rate can produce early ignition and cause an increase in the maximum in-cylinder pressure and the maximum average incylinder temperature.Moreover,in such conditions NO emissions are larger while soot emission is slightly lower.

摘要： Lignocellulosic biomass is a promising feedstock for the synthesis of value-added chemicals and biofuels.However,one of the biggest challenges for producing high-quality diesel fuels is the lack of sufficient carbon-chain length in biomass derivatives.In this study,a C_(17)diesel precursor 1,1,1-tris(5-methyl-2-f uryl)ethane(TEMF)with a yield of ca.70%was synthesized from the cascade acetylation-hydroxyalkyla tion/alkylation of bio-based 2-methylfuran(MF)with acetic anhydride(AA)catalyzed by acid-treated montmorillonite with enhanced acidity and improved porosity.The catalytic mechanism of the cascade reaction process was investigated over different types of acid species(Br?nsted acid and Lewis acid),and the influence of in situ formed acetic acid was also examined.A synergistic effect was observed to enable the synthesis of TEMF from the trimerization of MF with AA,in which Lewis acid and weak Br?nsted acid species mainly catalyze the acetylation and hydroxyalkylation processes,while the subsequent alkylation step is mainly catalyzed by strong Br?nsted acid.