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Here, the efficient synthesis of propylene from methanol was achieved using a series of HZSM-5 catalysts. The effect of the structure and morphology of ZSM-5 on the conversion of methanol to propylene was studied. The structure and physicochemical properties of the synthesized catalysts were analyzed by multiple characterization techniques. The characterization results revealed that the alumina content rationally modified the acid properties of ZSM-5. When using a ZSM-5 catalyst with a hexagonal single crystal and a Si/Al ratio of 177, the selectivity of propylene reached 39.7% at 480 °C. Furthermore, the formation of methane was reduced. This provides a clue for catalyst design to enable the selective transformation of methanol into propylene.

Here, we report a Na-promoted FeCu-based catalyst with excellent liquid hydrocarbon selectivity and catalytic activity. The physiochemical properties of the catalysts were comprehensively characterized by various characterization techniques. The characterization results indicate that the catalytic performance of the catalysts was closely related to the nature of the metal promoters. The Na-AlFeCu possessed the highest CO2 conversion due to enhanced CO2 adsorption of the catalysts by the introduction of Al species. The introduction of excess Mg promoter led to a strong methanation activity of the catalyst. Mn and Ga promoters exhibited high selectivity for light hydrocarbons due to their inhibition of iron carbides generation, resulting in a lack of chain growth capacity. The Na-ZnFeCu catalyst exhibited the optimal C5+ yield, owing to the fact that the Zn promoter improved the catalytic activity and liquid hydrocarbon selectivity by modulating the surface CO2 adsorption and carbide content. Carbon dioxide (CO2) hydrogenation to liquid fuel is considered a method for the utilization and conversion of CO2, whereas satisfactory activity and selectivity remains a challenge. This method provides a new idea for the catalytic hydrogenation of CO2 and from there the preparation of high-value-added products.

The direct selective conversion of ethanol to butadiene (ETB) is a competitive and environmentally friendly process compared to the traditional crude cracking route. The acid–base properties of catalysts are crucial for the direct ETB process. Herein, we report a rationally designed multifunctional lignin-derived carbon-modulated ZnZr/SiO2 (L-ZnZr/SiO2) catalyst with suitable acid–base properties for the direct ETB reaction. A variety of characterization techniques are employed to investigate the relationship between the acid–base properties and catalytic performance of the multifunctional lignin-modulated ZnZr/SiO2 catalysts. The results revealed that the rationally additional lignin-modulated carbon enhances both the acidity and basicity of the ZnZr/SiO2 catalysts, providing a suitable acid–base ratio that boosts the direct ETB reactivity. Meanwhile, the 1% L-ZnZr/SiO2 catalyst possessed ethanol conversion and butadiene selectivity as high as 98.4% and 55.5%, respectively, and exhibited excellent catalytic stability.

The process of Fischer–Tropsch synthesis is commonly described as a series of reactions in which CO and H2 are dissociated and adsorbed on the metals and then rearranged to produce hydrocarbons and H2O. However, CO dissociation adsorption is regarded as the initial stage of Fischer–Tropsch synthesis and an essential factor in the control of catalytic activity. Several pathways have been proposed to activate CO, namely direct CO dissociation, activation hydrogenation, and activation by insertion into growing chains. In addition, H2O is considered an important by-product of Fischer–Tropsch synthesis reactions and has been shown to play a key role in regulating the distribution of Fischer–Tropsch synthesis products. The presence of H2O may influence the reaction rate, the product distribution, and the deactivation rate. Focus on H2O molecules and H2O-derivatives (H*, OH* and O*) can assist CO activation hydrogenation on Fe- and Co-based catalysts. In this work, the intermediates (C*, O*, HCO*, COH*, COH*, CH*, etc.) and reaction pathways were analyzed, and the H2O and H2O derivatives (H*, OH* and O*) on Fe- and Co-based catalysts and their role in the Fischer–Tropsch synthesis reaction process were reviewed.

Although Fe-based catalysts have made significant progress in Fischer–Tropsch synthesis, the effect of residual sodium on the structural properties and catalytic performance of Fe-based catalysts has been controversial. Herein, we report the positive role of residual sodium in the structural properties and performance of FeAlNa catalysts for olefins synthesis from syngas. Meanwhile, the as-prepared catalysts were characterized by the multiple characterization technique to reveal the positive role of residual sodium on the structural properties. The characterization results revealed that the residual sodium improved the reduction behavior of Fe species and adsorption ability of CO, and inhibited the secondary hydrogenation due to its weak adsorption ability of H2. Moreover, the residual sodium inhibited the interaction between Fe and Al. Importantly, a high olefins/paraffins ratio of 6.19 and low CH4 selectivity of 12.8% were achieved on the residual sodium modified FeAlNa catalyst. An in-depth understanding of the structural properties and catalytic performance of residual sodium on FeAl-based catalysts can provide a theoretical basis for the development of novel efficient catalysts and large-scale applications for olefins synthesis from syngas.

Biodiesel is generally produced from vegetable oils and methanol, which also generates glycerol as byproduct. To improve the overall economic performance of the process, the selective formation of methanol from glycerol is important in biodiesel production. In the present study, a CaO modified HZSM-5 zeolite was prepared by an impregnation method and used for the conversion of glycerol to methanol. We found that the 10%CaO/HZSM-5 with Si/Al ratio of 38 exhibited highest selectivity to methanol of 70%, with a glycerol conversion of 100% under 340 ℃ and atmospheric pressure. The characterization results showed that the introduction of a small amount of CaO into the HZSM-5 did not affect the structure of zeolite. The incorporation of HZSM-5 as an acidic catalyst and CaO as a basic catalyst in a synergistic catalysis system led to higher conversion of glycerol and selectivity of methanol.

Biomass, the only renewable source of organic carbon, has been widely used and developed as a functional carbon material owing to its low cost and easy accessibility. In this study, a simple and green strategy to prepare an iron catalyst based on waste biomass (litchi shell, LC) as a catalyst carrier is proposed. The Fe/LC composite catalyst was prepared by the one-step carbonization of LC impregnated with iron nitrate to improve its dispersion. During CO2 hydrogenation, the biomass-based carbon material effectively inhibited the oxidation of water on the catalyst. Thus, the stability of the catalyst improved and the formation of olefins was significantly promoted, resulting in excellent catalytic performance. The optimized Fe/LC catalyst exhibited good catalytic performance for CO2 hydrogenation, and its selectivity for light olefins (C=2–4) was 47 wt% (olefin/alkane molar ratio = 3.1). The characterization results revealed the formation of a graphitic-carbon-anchored Fe3O4 structure during high-temperature carbonization. This structure played a coordinated role with the natural K minerals in LC, effectively improving the CO2-hydrogenation activity of the catalyst and increasing its selectivity for C=2–4 products. The direct use of waste biomass without any chemical pretreatment, purification, or addition of promoters provides a simple design method and synthesis strategy for the low-cost, large-scale preparation of high-performance carbon-based catalysts. [ABSTRACT FROM AUTHOR]

This paper presents a real-world auto-carrier loading and routing problem encountered by an automotive logistics company in China. The problem requires determining a set of routes for auto-carriers to transport vehicles from warehouses to dealers subject to several loading and routing constraints. Four objectives are considered, including the maximization of the number of loaded urgent vehicles and the number of loaded vehicles, and the minimization of the number of visits to dealers and travel distance. To solve such a multi-objective problem, we develop a two-stage iterated local search heuristic with the lexicographic optimization principle. Expressly, we assume that all vehicles are stored in one warehouse and solve the resulting problem as the first stage. Then the best-found solution is improved by considering the multiple warehouse constraints in the second stage. The effectiveness of the proposed heuristic is validated by comparing it with a commercial solver and the company’s approach. Moreover, computational results provide managerial insights for decision-makers when considering the objectives and their priorities in different scenarios. [ABSTRACT FROM AUTHOR]

In this paper, we address the problem of choosing an appropriate channel for the marketing channel structure of remanufactured fashion products. To be specific, we consider a remanufacturer who has two options for selling the products: (1) provide the remanufactured products to a manufacturer, then the manufacturer sells both new products and the remanufactured products to customers, and (2) sell the remanufactured products directly to customers. Because of the relatively low acceptance of remanufactured products and environment consciousness of customers in developing countries like China, we model the two scenarios as decentralized remanufacturing supply chains, with the manufacturer being the Stackelberg leader and the government offering subsidy to the remanufacturer to incentivize remanufacturing activities. We find that the subsidy can incentivize remanufacturing activity regardless of the remanufacturer's channel choice. A "too high" or "too low" subsidy makes the remanufacturer compete with the manufacturer, and an intermediate subsidy results in cooperation between the two members of the remanufacturing supply chain. Meanwhile, if the customers' acceptance for remanufactured products is higher, the remanufacturer will be more likely to compete with the manufacturer. However, the remanufacturer's optimal channel choice may be inefficient in the sense of social welfare and environmental protection. [ABSTRACT FROM AUTHOR]