B-COPNA resin formation from ethylene tar light fractions:Process development and mechanical exploration by molecular simulation

An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw materials.Under such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular simulation.The effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the process.The reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking agents.It was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking agents.In addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed aromatics.The corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular simulation.Hence,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.

Carbon-based derivatives from metal-organic frameworks as cathode hosts for Li–S batteries

Lithium-sulfur batteries(Li–S batteries) are promising candidates for the next generation high-energy rechargeable Li batteries due to their high theoretical specific capacity(1672 m Ahg-1) and energy density(2500 Wh kg-1). The commercialization of Li–S batteries is impeded by several key challenges at cathode side, e.g. the insulating nature of sulfur and discharged products(Li2S 2 and Li2S), the solubility of long-chain polysulfides and volume variation of sulfur cathode upon cycling. Recently, the carbonbased derivatives from metal-organic frameworks(MOFs) has emerged talent in their utilization as cathode hosts for Li–S batteries. They are not only highly conductive and porous to enable the acceleration of Li +/e-transfer and accommodation of volumetric expansion of sulfur cathode during cycling, but also enriched by controllable chemical active sites to enable the adsorption of polysulfides and promotion of their conversion reaction kinetics. In this review, based on the types of MOFs(e.g. ZIF-8, ZIF-67, Prussian blue, Al-MOF, MOF-5, Cu-MOF, Ni-MOF), the synthetic methods, formation process and morphology, structural superiority of MOFs-derived carbon frameworks along with their electrochemical performance as cathode host in Li–S batteries are summarized and discussed.

Effects of the Different Supports on the Activity and Selectivity of Iron-Cobalt Bimetallic Catalyst for Fischer-Tropsch Synthesis

Silica, alumina, and activated carbon supported iron-cobalt catalysts were prepared by incipient wetness impregnation. These catalysts have been characterized by BET, X-ray diffraction （XRD）, and temperature-programmed reduction （TPR）. Activity and selectivity of iron-cobalt supported on different carriers for CO hydrogenation were studied under the conditions of 1.5 MPa, 493 K, 630 h^-1, and H2/CO ratio of 1.6. The results indicate that the activity, C4 olefin/（C4 olefin＋C4 paraffin） ratio, and C5 olefin/（C5 olefin＋C5 paraffin） decrease in the order of Fe-Co/SiO2, Fe-Co/AC1, Fe-Co/Al2O3 and Fe- Co/AC2. The activity of Fe-Co/SiO2 reached a maximum. The results of TPR show that the Fe-Co/SiO2 catalyst is to some extent different. XRD patterns show that the Fe-Co/SiO2 catalyst differs significantly from the others; it has two diffraction peaks. The active spinel phase is correlated with the supports.

Pretreatment of Alumina and Its Influence on the Properties of Co/Alumina Catalysts for Fischer-Tropsch Synthesis

16.6%Co/γ-Al2O3 catalysts prepared by incipient wetness impregnation method were used for Fischer-Tropsch synthesis. The support was pre-treated with different concentration of NH4NO3 aqueous solution. The effect of support pre-treatment on the properties of support and performance of supportedcobalt-based catalysts was investigated. To treat the support with NH4NO3 aqueous solution enlarged the pore of γ-Al2O3, decreased the impurity Na2O content, and weakened the surface acidity of γ-Al2O3. The change in the properties of the support decreased the interaction between cobalt species and support, enhanced the CO hydrogenation rate and the C5＋ selectivity. For all catalysts, increasing the reaction temperature increased the CO hydrogenation rate or the CO conversion, slightly decreased the total hydrocarbon selectivity, and favored the formation of methane and light hydrocarbons, while the chain growth probability decreased. For 16.6%Co/γ-Al2O3 catalysts, prepared with the support treated with 100 g/L NH4NO3 aqueous solution, the CO conversion, the CH4 selectivity, and the C5＋ selectivity were 83.13%, 6.86% and 82.75% respectively, and the chain growth probability was 0.83 under the condition of 493 K, 1.5 MPa, 500 h-1 and the molar ratio of H2 to CO being 2.0 in feed.

Modification of FCC slurry oil and deoiled asphalt for making high-grade paving asphalt

With the rapid development of modern industry,high-grade paving asphalt is massively required to meet the demands for modern transportation.As one of additives,natural asphalt is indispensable since it can improve the performance of paving asphalt in all aspects.However,the application of non-renewable natural asphalt is increasingly restricted by its limited reserves.It is imperative to find alternative approaches to produce high-grade paving asphalt.Fluid catalytic cracking(FCC)slurry oil is an ideal soft component for producing paving asphalt due to its high content of aromatics and resins.However,its bad ageing resistance limits its application to only low-grade paving asphalt.In the present work,a novel approach for producing high-grade paving asphalt was investigated using chemically modified FCC slurry oil and deoiled asphalt(DOA).The FT-IR and NMR results showed that dehydrogenation and condensation reaction occurred during the ageing process.From a series of aliphatic alcohols and aldehydes,propanal was selected as a proper modifier to improve the ageing resistance of FCC slurry oil.The propanalmodified slurry oil possessed more substituted aromatic units and less aromatic hydrogen atoms than other modified slurry oils,thus showing better ageing resistance.With the increase of length of aliphatic chains in modifier,the modified slurry oil contained more and longer alkyl substituent group on aromatics.Compared with the cross-linked oil(slurry oil modified by cross-linking agent),modified slurry oil possessed similar ageing resistance but higher flowing ability.Also,the effect of operation conditions on the kinematic viscosity of modified slurry oil were investigated.Blended with modified slurry oil,the penetration ratio of asphalt product increased from 53.7 to 66.2,which met the standard of 70#paving asphalt.Both the microscopic observations and FT-IR results indicated that modification process effectively reduced the oxidation degree of asphalt product,thus increasing the ageing resistance.Consequently,with aid of this process,high-grade paving asphalt was readily produced from low value oil from downstream products of refinery,instead of the depleting natural asphalt.

Hydrodesulfurization catalyst prepared by urea-matrix combustion method

Co-Mo/γ-Al2O3-TiO2 hydrodesulfurization （HDS） catalyst samples prepared by a urea matrix combustion （UMxC） method, were evaluated in a stainless tubular fixed-bed reactor, with thiophene, benzothiophene and dibenzothiophene in xylene as model feedstocks. The samples were pre-sulfurized using a cyclohex- ane solution of 3% CS2 and then tested for the HDS reaction. The test results were compared with catalysts prepared by conventional methods involving sequential impregnation （SI） and co-impregnation （CI）. The catalysts were characterized using X-ray diffraction （XRD）, laser Raman spectroscopy （LRS）, high resolu- tion transmission electron microscopy （HRTEM） and N2 physisorption, showing that the UMxC catalyst had higher pore volume and surface area than those prepared by the CI and SI methods. The UMxC method increased metal loading and avoided formation of inert phase, e.g., β-CoMoO4, for the HDS reaction, sug- gesting that UMxC method is superior to the conventional impregnation techniques. TiO2 promoter made particles on the catalyst surface closer and alleviated the interaction between molybdenum oxide and the support, and facilitated the formation of well-dispersed Co- and Mo-oxo species on catalyst surface, thus resulting in higher HDS catalytic activity than pure γ-Al2O3 support without modifiers. Consequently, the addition of TiO2 obviously improved the HDS conversion of dibenzothiophene.

Thermodynamic analysis of liquid phase in situ hydrogenation of glycerol for 1,3-propanediol synthesis

Based on the combination of the glycerol aqueous-phase reforming(APR)and catalytic hydrogenation of glycerol,a novel reaction system of liquid phase in situ hydrogenation of glycerol for the synthesis of 1,3-propanediol is proposed,in which hydrogen is produced from glycerol aqueous-phase reforming in the same reactor.In this new system,the glycerol is the raw material of the aqueous-phase reforming reaction;the hydrogen generated from the APR of glycerol can be quickly transformed to the in situ hydrogenation of glycerol to produce 1,3-propanediol,which can improve the selectivity of hydrogen for the APR process of glycerol.Moreover,thermodynamic calculation of the coupling processes was carried out,and standard molar enthalpies and equilibrium constants of foregoing reactions were obtained.The above calculation results indicate that the combination process is feasible for 1,3-propanediol synthesis.