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"Hydrocracking"
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High-efficiency Ce-modified ZSM-5 nanosheets for waste plastic upgrading
Zeolite-based catalyst hydrocracking of plastics is a potential strategy for mitigating the environmental impacts of plastic wastes and recycling valuable resources, but difficult mass transfer, low concentration of acid sites, and high cost are still barriers to their practical applications. In this paper, we report an excellent hydrocracking catalyst of ZSM-5 nanosheets (Ce/b-ZSM-5) modified by Ce species with high conversion up to 96.3%, C
3
–C
5
selectivity up to 80.9%, and good stability during the hydrogenation of low-density polyethylene. Through comprehensive studies, b-ZSM-5 shows higher molecular diffusion efficiency and acid site concentrations compared with normal ZSM-5 (n-ZSM-5) and hollow ZSM-5 (h-ZSM-5). The introduction of Ce species into b-ZSM-5 further increases the density of Brønsted (B) and Lewis (L) acid sites as active sites, which enhances the adsorption of substrates and facilitates the formation of intermediates and desorption of products. As a result, the hydrocracking activity of Ce/b-ZSM-5 is significantly improved.
Journal Article
Mechanistic classification and benchmarking of polyolefin depolymerization over silica-alumina-based catalysts
Carbon-carbon bond cleavage mechanisms play a key role in the selective deconstruction of alkanes and polyolefins. Here, we show that the product distribution, which encompasses carbon range and formation of unsaturated and isomerization products, serves as a distinctive feature that allows the reaction pathways of different catalysts to be classified. Co, Ni, or Ru nanoparticles immobilized on amorphous silica-alumina, Zeo-Y and ZSM-5, were evaluated as catalysts in the deconstruction of
n
-hexadecane model substrate with hydrogen to delineate between different mechanisms, i.e., monofunctional- (acid site dominated) or bifunctional-hydrocracking (acid site & metal site) versus hydrogenolysis (metal site dominated), established from the product distributions. The ZSM-5-based catalysts were further studied in the depolymerization of polyethylene. Based on these studies, the catalysts are plotted on an activity-mechanism map that functions as an expandable basis to benchmark catalytic activity and to identify optimal catalysts that afford specific product distributions. The systematic approach reported here should facilitate the acceleration of catalyst discovery for polyolefin depolymerization.
Product distributions have been used to classify the depolymerization pathways of polyolefins catalyzed by silica-alumina-based catalysts to construct an activity-mechanism map as a benchmarking tool to facilitate catalyst discovery.
Journal Article
Experience in the operation of the Heavy Residue Conversion Complex (HRCC) based on VCC technology
The article presents a comparative assessment of various processes of demetallization of heavy petroleum feedstock (HPF). By the example of TAIF-NK JSC, which operates a slurry hydrocracking unit based on VCC process, the possibility of mastering secondary processes aimed at deepening oil refining is shown.
Journal Article
Carbon–carbon bond cleavage for a lignin refinery
Carbon–carbon bonds, ubiquitous in lignin, limit monomer yields from current depolymerization strategies, which mainly target C–O bonds. Selective cleavage of the inherently inert σ-type C–C bonds without pre-functionalization remains challenging. Here we report the breaking of C–C bonds in lignin obtained upon initial disruption of labile C–O bonds, achieving monocyclic hydrocarbon yields up to an order of magnitude higher than previously reported. The use of a Pt (de)hydrogenation function leads to olefinic groups close to recalcitrant C–C bonds, which can undergo β-scission over zeolitic Brønsted acid sites. After confirming that this approach can selectively cleave common C–C linkages (5–5′, β–1′, β–5′ and β–β′) in lignin skeletons, we demonstrate its utility in the valorization of various representative lignins. A techno-economic analysis shows the promise of our method for producing gasoline- and jet-range cycloalkanes and aromatics, while a life-cycle assessment confirms its potential for CO2-neutral fuel production.Carbon–carbon bonds are ubiquitous in lignin, limiting monomer yields from current depolymerization strategies mainly targeting C–O bonds. Now, a bifunctional hydrocracking approach uses a Pt/zeolite catalyst to break C–C bonds in lignin waste, achieving monocyclic hydrocarbon yields up to 54 C%.
Journal Article
Methods of Conversion of Residual Product of Combined Thermo- and Hydrocracking of Heavy Resid
The article is devoted to the experience of TAIF-NK JSC in the field of efficient, environment-friendly, and technological processing of residual products of combined thermo- and hydrocracking process with a comparative analysis of the merits and demerits of each method. It is shown experimentally that, taking into account the specific features of the residual products of hydrocracking and the associated increased tendency to precipitation of asphaltenes and coking, it is necessary to carry out further processing of residual products under milder conditions in order to get products that are in demand in metallurgy.
Journal Article
Unraveling the role of water in mechanism changes for economically viable catalytic plastic upcycling
The surge in global plastic production, reaching 400.3 million tons in 2022, has exacerbated environmental pollution, with only 11% of plastic being recycled. Catalytic recycling, particularly through hydrogenolysis and hydrocracking, offers a promising avenue for upcycling polyolefin plastic, comprising 55% of global plastic waste. This study investigates the influence of water on polyolefin depolymerization using Ru catalysts, revealing a promotional effect only when both metal and acid sites, particularly Brønsted acid site, are present. Findings highlight the impact of Ru content, metal-acid balance, and their proximity on this interaction, as well as their role in modulating the isomerization process, affecting product selectivity. Additionally, the interaction facilitates the suppression of coke formation, ultimately enhancing catalyst stability. A comprehensive techno-economic and life cycle assessment underscores the viability and environmental benefits of the process, particularly in the presence of water. These insights advance understanding and offer strategies for optimizing polyolefin plastic recycling processes.
Catalytic hydrogenolysis and hydrocracking present a promising approach for upcycling polyolefin plastics. Here, the authors highlight the role of water in catalytic plastic upcycling, emphasizing that catalysts with an optimal metal-acid balance significantly improve polyethylene depolymerization when water is present.
Journal Article
Porous Biochar Supported Transition Metal Phosphide Catalysts for Hydrocracking of Palm Oil to Bio-Jet Fuel
The upgrading of plant-based oils to liquid transportation fuels through the hydrotreating process has become the most attractive and promising technical pathway for producing biofuels. This work produced bio-jet fuel (C9–C14 hydrocarbons) from palm olein oil through hydrocracking over varied metal phosphide supported on porous biochar catalysts. Relative metal phosphide catalysts were investigated for the highest performance for bio-jet fuel production. The palm oil’s fiber-derived porous biochar (PFC) revealed its high potential as a catalyst supporter. A series of PFC-supported cobalt, nickel, iron, and molybdenum metal phosphides (Co-P/PFC, Ni-P/PFC, Fe-P/PFC, and Mo-P/PFC) catalysts with a metal-loading content of 10 wt.% were synthesized by wet-impregnation and a reduction process. The performance of the prepared catalysts was tested for palm oil hydrocracking in a trickle-bed continuous flow reactor under fixed conditions; a reaction temperature of 420 °C, LHSV of 1 h−1, and H2 pressure of 50 bar was found. The Fe-P/PFC catalyst represented the highest hydrocracking performance based on 100% conversion with 94.6% bio-jet selectivity due to its higher active phase dispersion along with high acidity, which is higher than other synthesized catalysts. Moreover, the Fe-P/PFC catalyst was found to be the most selective to C9 (35.4%) and C10 (37.6%) hydrocarbons.
Journal Article
Roles of Catalysts and Feedstock in Optimizing the Performance of Heavy Fraction Conversion Processes: Fluid Catalytic Cracking and Ebullated Bed Vacuum Residue Hydrocracking
Petroleum refining has been, is still, and is expected to remain in the next decades the main source of energy required to drive transport for mankind. The demand for automotive and aviation fuels has urged refiners to search for ways to extract more light oil products per barrel of crude oil. The heavy oil conversion processes of ebullated bed vacuum residue hydrocracking (EBVRHC) and fluid catalytic cracking (FCC) can assist refiners in their aim to produce more transportation fuels and feeds for petrochemistry from a ton of petroleum. However, a good understanding of the roles of feed quality and catalyst characteristics is needed to optimize the performance of both heavy oil conversion processes. Three knowledge discovery database techniques—intercriteria and regression analyses, and artificial neural networks—were used to evaluate the performance of commercial FCC and EBVRHC in processing 19 different heavy oils. Seven diverse FCC catalysts were assessed using a cascade and parallel fresh catalyst addition system in an EBVRHC unit. It was found that the vacuum residue conversion in the EBVRHC depended on feed reactivity, which, calculated on the basis of pilot plant tests, varied by 16.4%; the content of vacuum residue (VR) in the mixed EBVRHC unit feed (each 10% fluctuation in VR content leads to an alteration in VR conversion of 1.6%); the reaction temperature (a 1 °C deviation in reaction temperature is associated with a 0.8% shift in VR conversion); and the liquid hourly space velocity (0.01 h-1 change of LHSV leads to 0.85% conversion alteration). The vacuum gas oil conversion in the FCC unit was determined to correlate with feed crackability, which, calculated on the basis of pilot plant tests, varied by 8.2%, and the catalyst ΔCoke (each 0.03% ΔCoke increase reduces FCC conversion by 1%), which was unveiled to depend on FCC feed density and equilibrium FCC micro-activity. The developed correlations can be used to optimize the performance of FCC and EBVRHC units by selecting the appropriate feed slate and catalyst.
Journal Article