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We prepared a series of highly dispersed tetrahedrally coordinated tungsten catalysts with different Si/Al ratios by a simple "top-down" method for catalytic cracking of 1-hexene to propene. High 1-hexene conversion (>97%) and propene selectivity (>40%) could be maintained at 575°C over the W-ZSM-5(60) catalyst. [Display omitted] • Stability of the Si-O-Al structure in the W-ZSM-5 framework was enhanced. • Active tetrahedrally coordinated W (VI) species were highly dispersed on ZSM-5 catalysts. • Superior propene selectivity was achieved over W-ZSM-5 (60) catalysts. • The mechanism of W-ZSM-5 on the 1-hexene cracking reaction path were clarified. Reasonable regulation of the acidity of ZSM-5 could fundamentally improve the catalytic performance for the cracking of low-carbon olefins to propene. Herein, a series of ZSM-5 catalysts with highly dispersed tetrahedrally coordinated W(VI) species were prepared for the catalytic cracking of 1-hexene to propene by a simple "top-down" method. Multi-characterizations revealed that the introduction of W enhanced the stability of the Si-O-Al structure in W-ZSM-5 by eliminating the non-skeleton aluminum and excessive Brønsted acid sites, leading to a superb resistance to carbon/coke deposition. Moreover, the Lewis acid sites originated from the active tetrahedrally coordinated W (VI) species improved the propene selectivity via inhibiting the polymerization of products. In addition, through the optimization of various parameters (such as Si/Al ratio, temperature and weight hourly space velocity), high 1-hexene conversion (>97%) and propene selectivity (>40%) could be maintained at 575 °C over the W-ZSM-5(60) catalyst during 30 h long period reaction. This work may provide some new insights for the effect of W-based catalysts on acid composition in the cracking of light olefins to propene. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT) calculation and microkinetic analysis, metal single-atom-doped ZSM-5 zeolite catalysts for naphtha cracking are screened. The calculation results show that the strong electronic interaction between metal single atom and zeolite skeleton (especially Ag and Cu) could enhance structural stability. The volcanic diagram of turnover frequency shows that Ag and Cu doped ZSM-5 zeolite catalyst is at the top of the volcano, which is close to the best choice. [Display omitted] • Metal single-atom-doped ZSM-5 zeolite catalyst exhibits good structural stability. • The adsorption of naphtha hydrocarbon molecules and the activation of C–H bond are greatly promoted. • The binding energy of carbon and hydrogen can be used as a descriptor for the catalytic cracking of naphtha on M−ZSM−5. • Ag and Cu single-atom-doped ZSM-5 are predicted to exhibit excellent catalytic activity. • Mo and Pd single-atom-doped ZSM-5 display great potential in the enhancement of propylene selectivity. Metal doped ZSM-5 catalyst has attracted much attention due to its unique catalytic activity for C–H bond activation. In this work, based on density functional theory (DFT) calculations and microkinetic analysis, we prospectively explored the catalytic activity of 12 kinds of transition metals (M = Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Pt, Au) single-atom-doped ZSM-5 zeolite catalysts in the catalytic cracking of naphtha. The results show that there is a strong electronic interaction between metal atom and ZSM-5 skeleton. This induced stable structure could improve the adsorption ability of hydrocarbon, thus promoting the activation of C–H bond and the cracking of carbenium ion. Moreover, C and H binding energy were identified as descriptors in describing catalytic activity via good scaling relations. The turnover frequency volcano diagram shows that the Ag and Cu doped ZSM-5 zeolite catalyst is close to the best choice. In addition, Pd and Mo are potential metal choices with good selectivity through selectivity analysis. This work has important guiding significance for understanding the fluid catalytic cracking (FCC) mechanism and designing high-efficiency cracking catalysts. [ABSTRACT FROM AUTHOR]

This study proposed a synergistic catalysis effect of micro-mesoscopic channel for enhanced methyl oleate catalytic cracking to BTX inside the hierarchical ZSM-5 zeolites via molecular simulation. Such synergistic catalysis effect could increase the BTX yield by enhancing the adsorption of the reaction substrate, facilitating the transfer of the as-formed C 3 H 6 and C 4 H 8 from mesopore into micropore and accelerating the rapid diffusion of BTX to mesopore. [Display omitted] • Synergistic catalysis effect of micro-mesoscopic channel for enhanced methyl oleate catalytic cracking to BTX is proposed. • Microporous and hierarchical ZSM-5 zeolite models have been constructed that are consistent with the experimental properties. • Pioneering study of the adsorption properties of long-chain molecules inside hierarchical zeolite. • Channel dependence to produce BTX inside two zeolites is systematically discussed. The hierarchical ZSM-5 zeolite exhibits superior catalytic performance for methyl oleate catalytic cracking to BTX, while the promotion mechanism at the molecular level is still unclear. Herein, the adsorption and diffusion behaviors of reaction species in hierarchical ZSM-5 zeolite, including methyl oleate, C 3 H 6 , C 4 H 8 and BTX, were theoretically investigated by Monte Carlo combined with Molecular Dynamics simulation. It is found that the introduction of mesopores exposes the strong adsorption sites (Brønsted acid) without a confinement effect, thereby promoting the adsorption and cracking of methyl oleate. Moreover, the as-formed C 3 H 6 and C 4 H 8 rapidly transfer from mesopore into micropore, enhancing the aromatization reaction to form BTX. Finally, thanks to the adjacent mesopore providing sufficient space for molecule rotation, the desired BTX products easily desorbs from the micropore. Such synergistic catalysis effect of micro-mesoscopic channel increases the BTX yield by decreasing the diffusion coefficient of C 3 H 6 and C 4 H 8 from 13.2 × 10-9 m2/s on the traditional to 6.4 × 10-9 m2/s on the hierarchical ZSM-5. We anticipate that this work could enrich our understanding of the microcosmic mechanism of hierarchical zeolites for prolific aromatics. [ABSTRACT FROM AUTHOR]

Waste plastics catalytic cracking, a carbon-negative process from the life cycle perspective, is a forceful executable configuration for cyclic utilization in the ecology. However, industrializing this emerging process requires to prevail a series of challenges, including time-consuming and massive pilot tests, process strengthening, and parameter optimization. To accelerate industrialization, we developed a fraction-structure lumps reaction model that significantly improves efficiency and accuracy. Moreover, multi-objective optimization and multi-dimensional evaluation were further done by implementing this process model. Together, a subsequent assessment of society and the environment was carried out. Compared with the non-optimized process, the optimized waste plastic catalytic cracking process exhibits superior economic, social, and environmental performance. The final optimization results of the reaction temperature and catalyst/oil ratio are 564.27 and 25.95, respectively. Quantitative results of this study indicate that catalytic cracking of waste plastics can effectively reduce the emissions of 1.86 t CO 2 eq/t feedstocks. For the 200,000-ton scale waste plastic catalytic cracking process constructed, it can effectively reduce 372,000 tons of carbon dioxide equivalent emissions annually. From the view of life cycle society-environment behavior, it can be intuitively seen that the primary energy consumption of the WPCC-Pro process optimized based on the same functional units (considering social and environmental factors) is better than that of the WPCC process. [Display omitted] • The fraction-structure lumps reaction model of waste plastic catalytic cracking is proposed. • The many-objective optimization framework is employed. • The waste plastic catalytic cracking-pro process exhibits excellent life cycle performance. [ABSTRACT FROM AUTHOR]

Achieving direct catalytic cracking of crude oil to produce low-cost petrochemicals is a milestone technology for the transformation of refinery from "fuel type" to "chemical engineering type". Herein, we first established the crude oil catalytic cracking process and identified the key process parameters affecting ethylene and propylene yields. Meanwhile, the crude oil direct steam cracking process was selected as a comparative process for the process economic, social and environmental performance by an improved life cycle society-environment assessment method. The improvement direction, suitable preheating temperature and higher cracking temperature, are given from the aspect of process though systematic integration and intensification. Results show the conversion rate of the catalytic cracking process is 86.10%, while the steam cracking process is only 76.71%. Furthermore, the utilization efficiency of carbon and hydrogen in the catalytic cracking process is 1.29 and 1.47 times higher than the steam cracking process, respectively. As for the society-economic performance, the catalytic cracking process provides up to 65% and 11% increase in net present value and total output value. As for the environmental performance, the catalytic cracking process consumes approximately 4% less non-renewable energy and has 31% less waste water generation. The results in this study harbour tremendous guiding significance to the design of crude oil directly efficient conversion to petrochemicals. With fuel consumption expected to wane, crude-to-chemicals complexes could dominate the petrochemical industry in the future. As a promising process for industrial application, direct catalytic cracking of crude oil has attracted many scientific institutions and companies to invest in the research wave. However, there have been widely differing versions on the performance of direct steam cracking and catalytic cracking processes from the perspective of techno-economy, society and environment. Based on the industrial and pilot-test data, this paper constructs process models for crude-to-chemicals, and gives a clear and quantitative answer to the performance of economic and carbon emission from the perspective of society-environment. [Display omitted] • Direct steam cracking and catalytic cracking of crude oil processes are simulated. • An improved life cycle society-environment assessment method is adopted. • The economic and environment performance of two processes are compared quantitatively. • The crude oil catalytic cracking process exhibits superior performance. [ABSTRACT FROM AUTHOR]

This study introduces a universality methodology to achieve the jumped chemical output of crude oil via one-step leaping over regular routes using the patented two-segment lift tube reactor. The integrated molecular-level modeling as well as many-objective optimization framework for crude oil direct hydrogenation coupled with a catalytic cracking reaction process using the two-segment lift tube reactor (CDHC) is also performed. Consequently, the CDHC process could solidly transform hydrotreated sulfur oil to chemicals with the sum of yields over 43 wt%. The non-renewable energy consumption of the optimized CDHC process decreased by 5.00%, the greenhouse gas emissions decreased by 4.09%, and the number of potential jobs available increased by 9.35%. This shows the leading technique, economics, livelihood, society, and environment character. The insights provided in this study may strongly promote the conceptual process design, engineering intensification together with many-objective optimization of oil direct hydrotreating coupled with catalytic cracking. This work developed the jumped chemical output of crude oil via one-step leaping over regular routes, an integrated molecular-level modeling strategy and a many-objective optimization framework. [Display omitted] [ABSTRACT FROM AUTHOR]

Our study developed the one-step catalytic cracking conceptual design using a two-stage riser reactor (OSCO). Molecular-level process models and multi-objective optimization strategies are also carried out. Results show that the OSCO process exhibits superior techno-economic, society, people's livelihood, and environmental performance. [Display omitted] • A novel process is proposed to crack naphtha, kerosene, diesel and heavy oil in the two-stage riser reactor efficiently. • A novel integration model of mixed fraction structure and molecular level is proposed. • The multi-objective optimization strategies using systematic solution algorithm are performed. • The novel process shows superior techno-economic, society, people's livelihood, and environmental performance. With the demand for vehicle fuels (i.e., gasoline and diesel) is expected to decline soon, crude oil to chemical technology exhibits great potential to drive the next industry transition. This megatrend has led to studies on maximizing the production of low-carbon petrochemicals at the cost of fuels, which requires aggressive ways of converting oil into chemicals in a clean and efficient pattern. Herein, we proposed a novel process, termed OSCO, to crack naphtha, kerosene, diesel and heavy oil in a two-stage riser reactor efficiently, which can perform several refining procedures in the two-stage riser reactor vessel. A novel integration model of mixed fraction structure and molecular level is proposed. The multi-objective optimization strategies are also carried out to solve the optimization problem. As a result, the OSCO process can stably convert untreated heavy Daqing crude oil into light olefins with total yields of ethylene and propylene over 33 wt%, which also exhibits superior techno-economic, society, people's livelihood, and environmental performance. These insights may have a positive pushing role in engineering design, process intensification, and the optimization of direct catalytic cracking of crude oil. [ABSTRACT FROM AUTHOR]

• Developing a novel DHTMP process to enhance naphthenic heavy oil to petrochemicals. • Detailed process simulation, operating parameters optimization are conducted. • System comparison of four naphthenic-based heavy oil processes are carried out. • The DHTMP process has favorable techno-economic and environment performance. Global excess capacity of lubricating oil and high-value added utilization of naphthenic-based heavy oil concerns have attracted tremendous attention. Enhancing the highly efficient transformation for polycyclic aromatic hydrocarbons (PAHs) rich in naphthenic-based vacuum gas oil to light olefins and aromatics could be a promising solution through systematic process integration. Four naphthenic-based heavy oil processing schemes, hydrotreating, hydrocracking, hydro-upgrading and deep catalytic cracking, and a novel deep hydrogenation coupled with the two stage risers of maximizing propylene process (DHTMP), are brought up. The process simulation and models are established for the processing schemes to gain detailed mass balance and energy consumption results. The operating parameters are optimized for the purpose of maximizing light olefins and aromatics. The economic and life cycle environmental assessment are conducted to determine the superiority of DHTMP process over other schemes. The DHTMP process realized full recovery and utilization of low-value light cycle oil and efficient transformation of PAHs to light olefins and aromatics. Moreover, the DHTMP process shows great performance from the techno-economic and life cycle environment aspect. The results in this study have great guiding significance to the process intensification of PAHs in vacuum gas oil converting to light olefins and aromatics products efficiently. Image, graphical abstract [ABSTRACT FROM AUTHOR]