Enhancing the production of light olefins from heavy crude oils: Turning challenges into opportunities

Synthesis of Ordered Mesoporous Molecular Sieve-Supported Cobalt Catalyst via Organometallic Complexation for Propane Non-Oxidative Dehydrogenation

Co-based catalysts have shown great promise for propane dehydrogenation (PDH) reactions due to their merits of environmental friendliness and low cost. In this study, ordered mesoporous molecular sieve-supported CoOx species (CoOx/Al-SBA-15 catalyst) were prepared by one-step organometallic complexation. The catalysts show worm-like morphology with regular straight-through mesoporous pores and high external specific surface area. These typical features can substantially enhance the dispersion of CoOx species and mass transfer of reactants and products. Compared with the conventional impregnation method, the 10CSOC (10 wt.% Co/Al-SBA-15 prepared by the organometallic complexation method) sample presents a smaller CoOx size and higher Co2+/Co3+ ratio. When applied to PDH reaction, the 10CSOC delivers higher propane conversion and propylene selectivity. Under the optimal conditions (625 °C and 4500 h-1), 10CSOC achieves high propane conversion (43%) and propylene selectivity (83%). This is attributed to the smaller and better dispersion of CoOx nanoparticles, more suitable acid properties, and higher content of Co2+ species. This work paves the way for the rational design of high-performance catalysts for industrially important reactions.

From bench to industry, the application of all-inorganic solid base materials in traditional heterogeneous catalysis: a mini review

Acids and bases generally occur in pairs as concepts, and a large number of catalytic reactions can be considered as interactions between acids and bases. Many chemical reactions are a combination of acid-catalyzed processes and base-catalyzed processes, and thus it is particularly important to study and explain the mechanisms of acid-base synergy or acid-base interactions. However, compared to the in-depth research on acid catalysts, there is a lack of research on solid bases. In addition to the application of basic materials to non-petroleum processes, recent studies have also applied basic materials to the catalytic cracking reaction process of heavy oils, providing new ideas for the processing of heavy oils. The formation of carbanions with the contribution of basicity is a critical stage in many fine chemical reactions, as well as in the hydrocarbon cracking reactions promoted by a base. Thus, herein, we summarize the research progress on the main types of all-inorganic solid base catalysts, including the types of catalysts used in non-petroleum processes and petroleum processes, their preparation, the properties of their basic sites, and their structure-performance correlation in the reactions. Also, we provide an outlook on the future research directions of all-inorganic solid base materials.

Roles of ethanol in coke formation and HZSM-5 deactivation during n-heptane catalytic cracking

Compared with n-heptane, ethanol easily interacted with the acid site of HZSM-5, promoting alkene and external coke formation.

Exergy analysis of an atmospheric residue desulphurization hydrotreating process for a crude oil refinery

The exhaustion of petroleum reserves and the declining supply of conventional feedstock have forced refineries to use heavier crude oil in their production. Removing the undesirable components containing sulphur and metals in the atmospheric residue (AR) fraction requires extensive catalytic hydrotreating (HT) atmospheric residue desulphurization (ARDS) process. In this work, we endeavour to collect and present a comprehensive dataset to develop and simulate the ARDS HT model. This model is then used for an exergetic analysis to evaluate the performance of the ARDS HT model regarding the exergy destruction, the location of losses and exergetic efficiency. The massive exergy destruction is caused by significant differences in chemical exergy of source and product streams during separations, fractionation and reactions. The exergy destruction in the equipment independent of chemical exergies such as heat exchangers, pumps and compressors is relatively low. This exergetic analysis revealed that the majority of the processing equipment in the ARDS HT process performed satisfactorily. However, the remaining equipment requires improvement for its performance in regards to exergetic efficiency or/and avoidable exergetic losses. To enhance the efficiency of the equipment that is intensive in terms of exergy and energy use, the use of clean and high purity renewable hydrogen and several process rectification is proposed.

Hydrodesulfurization of 4,6-Dimethyldibenzothiophene and the Diesel Oil Fraction on NiMo Catalysts Supported over Proton-Exchanged AlMCM-41 and TiMCM-41 Extrudates

NiMo catalysts supported on mesoporous MCM-41 type materials shaped with binder were tested for activity in the hydrodesulfurization of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and the diesel fuel fraction (0.92 wt% of sulfur). The aim of the investigation was to evaluate the effect of ion exchange with protons of Al- or Ti-substituted MCM-41 mesoporous supports. The subjected catalytic systems were NiMo/HAlMCM-41 and NiMo/HTiMCM-41, and for comparison purposes NiMo/AlMCM-41 and NiMo/TiMCM-41. The samples were characterized by N2 sorption (at 77 K), XRD, TEM, XPS, SEM and Py–IR. It was found that the functionalization of AlMCM-41 and TiMCM-41 with protons increased the conversion of 4,6-DMDBT and the pseudo-first-order rate constant. Correspondingly, 4,6-DMDBT HDS reactions over the NiMo/HTiMCM-41 catalyst proceeded to a similar extent via hydrogenation and direct desulfurization, whereas over the NiMo/HAlMCM-41 they proceeded mainly via direct desulfurization. Furthermore, the ion-exchanged catalysts displayed two-fold higher efficiency in direct desulfurization than their non-modified counterparts. The NiMo/HTiMCM-41 catalyst exhibited the highest catalytic efficiency in the HDS of 4,6-DMDBT and the diesel oil fraction. The high activity of the NiMo/HTiMCM-41 catalyst is mainly attributed to its appropriate acidity, as well as the metal–support interaction providing both the high dispersion of the active phase and the desirable multilayered stacking morphology of the active phase slabs.

Fischer–Tropsch Synthesis for Light Olefins from Syngas: A Review of Catalyst Development

Light olefins as one the most important building blocks in chemical industry can be produced via Fischer–Tropsch synthesis (FTS) from syngas. FT synthesis conducted at high temperature would lead to light paraffins, carbon dioxide, methane, and C5+ longer chain hydrocarbons. The present work focuses on providing a critical review on the light olefin production using Fischer–Tropsch synthesis. The effects of metals, promoters and supports as the most influential parameters on the catalytic performance of catalysts are discussed meticulously. Fe and Co as the main active metals in FT catalysts are investigated in terms of pore size, crystal size, and crystal phase for obtaining desirable light olefin selectivity. Larger pore size of Fe-based catalysts is suggested to increase olefin selectivity via suppressing 1-olefin readsorption and secondary reactions. Iron carbide as the most probable phase of Fe-based catalysts is proposed for light olefin generation via FTS. Smaller crystal size of Co active metal leads to higher olefin selectivity. Hexagonal close-packed (HCP) structure of Co has higher FTS activity than face-centered cubic (FCC) structure. Transition from Co to Co3C is mainly proposed for formation of light olefins over Co-based catalysts. Moreover, various catalysts’ deactivation routes are reviewed. Additionally, techno-economic assessment of FTS plants in terms of different costs including capital expenditure and minimum fuel selling price are presented based on the most recent literature. Finally, the potential for global environmental impacts associated with FTS plants including atmospheric and toxicological impacts is considered via lifecycle assessment (LCA).

A Review on Production of Light Olefins via Fluid Catalytic Cracking

The fluid catalytic cracking (FCC) process is an alternative olefin production technology, with lower CO2 emission and higher energy-saving. This process is used for olefin production by almost 60% of the global feedstocks. Different parameters including the operating conditions, feedstock properties, and type of catalyst can strongly affect the catalytic activity and product distribution. FCC catalysts contain zeolite as an active component, and a matrix, a binder, and a filler to provide the physical strength of the catalyst. Along with the catalyst properties, the FCC unit’s performance also depends on the operating conditions, including the feed composition, hydrocarbon partial pressure, temperature, residence time, and the catalyst-to-oil ratio (CTO). This paper provides a summary of the light olefins production via the FCC process and reviews the influences of the catalyst composition and operating conditions on the yield of light olefins.

Una mirada al desarrollo de aditivos reductores de viscosidad y sus aplicaciones en el transporte de crudos pesados

La presente revisión aborda la problemática que presentan los crudos pesados debido a su alta viscosidad, lo cual dificulta su transporte por tubería y su directa relación con la fracción de asfaltenos, cuyo apilamiento genera cambios en la reología del crudo, altas caídas de presión y mayores requerimientos energéticos en el bombeo, e incluso taponamiento de tuberías. Las investigaciones reportadas se han enfocado en predecir y elucidar la composición estructural de los asfaltenos, de lo cual se resaltan modelos que describen a los asfaltenos como sistemas de anillos aromáticos policondensados, que pueden unirse por interacciones de Van der Waals formando agregados, o también como estructuras jerárquicas de sistemas de anillos de hidrocarburos aromáticos policíclicos (PAH), que finalizan en la formación de racimos (clúster). También se resalta el modelo termodinámico coloidal, el cual predice moléculas de asfaltenos suspendidas en una fase líquida, estabilizada por resinas adsorbidas en su superficie. Una alternativa para disminuir la viscosidad de los crudos es la inclusión de aditivos, los cuales mediante interacciones moleculares apropiadas, generan la dispersión de agregados asfalténicos, reflejándose en la disminución de la viscosidad. Por ello a la hora de diseñar aditivos reductores de viscosidad pare crudos, es importante diseñar estructuras moleculares con determinados grupos funcionales asociados a aminas, amidas, alcoholes, ácidos, entre otros, que favorezcan interacciones que generen la dispersión de asfaltenos. Por ellos y con el fin de brindar un panorama amplio de esta línea de investigación tan extensa, se finaliza este documento con una revisión de algunos aditivos reductores de viscosidad, implementados por diferentes investigadores.

Organometal-catalyzed synthesis of high molecular weight poly-(l-lactic acid) with a covalently attached imidazolium salt: performance-enhanced reduced graphene oxide–PLLA biomaterials

Herein, we report on the synthesis of imidazolium salt end-functionalized PLLA (PLLA-IS) and its application in the preparation of reduced graphene oxide–PLLA composites.