A detailed study of the activity and deactivation of zeolites in hybrid Co/SiO2-zeolite Fischer–Tropsch catalysts

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.

Redefining the Symphony of Light Aromatic Synthesis Beyond Fossil Fuels: A Journey Navigating through a Fe-Based/HZSM-5 Tandem Route for Syngas Conversion

The escalating concerns about traditional reliance on fossil fuels and environmental issues associated with their exploitation have spurred efforts to explore eco-friendly alternative processes. Since then, in an era where the imperative for renewable practices is paramount, the aromatic synthesis industry has embarked on a journey to diversify its feedstock portfolio, offering a transformative pathway toward carbon neutrality stewardship. This Review delves into the dynamic landscape of aromatic synthesis, elucidating the pivotal role of renewable resources through syngas/CO2 utilization in reshaping the industry's net-zero carbon narrative. Through a meticulous examination of recent advancements, the current Review navigates the trajectory toward admissible aromatics production, highlighting the emergence of Fischer-Tropsch tandem catalysis as a game-changing approach. Scrutinizing the meliorated interplay of Fe-based catalysts and HZSM-5 molecular sieves would uncover the revolutionary potential of rationale design and optimization of integrated catalytic systems in driving the conversion of syngas/CO2 into aromatic hydrocarbons (especially BTX). In essence, the current Review would illuminate the path toward cutting-edge research through in-depth analysis of the transformative power of tandem catalysis and its capacity to propel carbon neutrality goals by unraveling the complexities of renewable aromatic synthesis and paving the way for a carbon-neutral and resilient tomorrow.

Effect of Changing Amounts of Promoters and Base Fe Metal in a Multicomponent Catalyst Supported on Coal-Based Activated Carbon for Fischer–Tropsch Synthesis

The effect of varying the amounts of metals Fe, Cu, K, and Mo was studied on a catalyst supported on activated carbon (AC), which is an item of novelty of this paper. The base-case catalyst contains 16% Fe, 0.9% K, 6% Mo, and 0.8% Cu relative to the AC support. For all of the catalysts used, alcohol production is small. The production of hydrocarbons depends upon the amount of Fe and other promoters used. The amount of Fe was increased from 0% to 32% on the catalyst containing base-case amounts of the other materials. While 0% Fe shows no activity towards Fischer–Tropsch synthesis (FTS), 32% Fe shows a marginal increase in FTS activity when compared with 16% Fe. Furthermore, the amount of K was increased from 0% to 1.8%, with the other metals in their base-case amounts. The selectivity of C1–C4 decreases with the addition of K, while the selectivity of C5+ increases. Analogously, the amount of Mo was increased from 0% to 12%. A small amount of Mo results in an increase in FTS activity but decreases with the addition of more Mo. Cu on the catalyst was increased from 0% to 1.6%, with 0.8% Cu proving optimum for FTS.

Cobalt hybrid catalysts in Fischer-Tropsch synthesis

Currently, cobalt and zeolites are used in Fischer-Tropsch synthesis (FTS) to produce gasoline-range hydrocarbons (GRHs) that constitute clean and environmentally friendly fuels. This technology has earned a great deal of attention from researchers across the world, as it provides a substitute for fuel derived from fossil crudes, which have hitherto been the sole source of the petrol and diesel required by the industry. However, owing to the depletion of the earth’s oil and coal reserves and the unfavourable environmental impact of conventional fuel production, an alternative source of fuel is needed. This article provides a critical review of the technological challenges involved in producing middle isoparaffins and olefins (gasoline hydrocarbons) by FTS. These involve combining cobalt-based catalysts and zeolites to form hybrid catalysts. In this review, we address most of these by setting out each method of creating cobalt and zeolite hybrid catalysts in turn, so that researchers can identify which applications are most effective for producing GRHs.

Preliminary evaluation of a commercially viable Co-based hybrid catalyst system in Fischer–Tropsch synthesis combined with hydroprocessing

A hybrid catalyst for one-step conversion of syngas into liquid hydrocarbons, mainly gasoline and diesel, is proposed.

Modeling the kinetics of cobalt Fischer-Tropsch catalyst deactivation trends through an innovative modified Weibull distribution

Since the increase in clean energy demand is driven by environmental concerns, energy management is an ever-lasting issue globally. Among the different scenarios for energy manufacturing, the catalytic route through the famous process named Fischer-Tropsch Synthesis provides beneficial consequences including pollution reduction and economic efficiency, among others. In this regard, catalyst stability must be taken into account as a crucial performance parameter, especially in the expensive cobalt-catalyzed CO hydrogenation processes. As catalyst deactivation seems to be inevitable in catalytic processes, deactivation issues such as the extent, failure rate, or reactivation significantly influence the exploration, development, design, and operation of commercial processes. Accordingly, the deactivation trend of a cobalt-based catalyst was modeled via an innovative Weibull distribution base, which presents a significant advance over the existing macroscopic deactivation models. Being employed to obtain informative equations, the model parameters provide valuable information about the catalyst lifetime, which can be used as a useful predictive tool for industrial control purposes.

The deactivation of a ZnO doped ZrO2–SiO2catalyst in the conversion of ethanol/acetaldehyde to 1,3-butadiene

A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO₂–SiO₂ catalyst prepared by a sol–gel method was performed. The samples were characterized by N₂ adsorption–desorption isotherms, scanning electron microscopy (SEM), NH₃ temperature programmed desorption (NH₃-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), ¹³C magic-angle spinning nuclear magnetic resonance (¹³C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn_0.5–Zr–Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C–O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.

Deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO–ZrO₂–SiO₂ catalyst.

Role of mesopores in Co/ZSM-5 for the direct synthesis of liquid fuel by Fischer–Tropsch synthesis

In a complex reaction system, in which gas, liquid, and solid catalysts work together, understanding the impact of mass transfer that varies with the catalyst pore structure is very challenging but also essential to designing selective catalysts.

Influence of oxalate ligand functionalization on Co/ZSM-5 activity in Fischer Tropsch synthesis and hydrodeoxygenation of oleic acid into hydrocarbon fuels

Achieving high degree of active metal dispersions at the highest possible metal loading and high reducibility of the metal remains a challenge in Fischer Tropsch synthesis (FTS) as well as in hydrogeoxygenation (HDO).This study therefore reports the influence of oxalic acid (OxA) functionalization on the metal dispersion, reducibility and activity of Co supported ZSM-5 catalyst in FTS and HDO of oleic acid into paraffin biofuel. The Brunauer–Emmett–Teller (BET) results showed that cobalt oxalate supported ZSM-5 catalyst (CoOx/ZSM-5) synthesized from the incorporation of freshly prepared cobalt oxalate complex into ZSM-5 displayed increase in surface area, pore volume and average pore size while the nonfunctionalized cobalt supported on ZSM-5 (Co/ZSM-5) catalyst showed reduction in those properties. Furthermore, both XRD and XPS confirmed the presence of Co° formed from the decomposition of CoOx during calcination of CoOx/ZSM-5 under inert atmosphere. The HRTEM showed that Co species average particle sizes were smaller in CoOx/ZSM-5 than in Co/ZSM-5, and in addition, CoOx/ZSM-5 shows a clear higher degree of active metal dispersion. The FTS result showed that at CO conversion over Co/ZSM-5 and CoOx/ZSM-5 catalysts were 74.28% and 94.23% and their selectivity to C₅₊ HC production were 63.15% and 75.4%, respectively at 4 h TOS. The HDO result also showed that the CoOx/ZSM-5 has higher OA conversion of 92% compared to 59% over Co/ZSM-5. In addition CoOx/ZSM-5 showed higher HDO and isomerization activities compared to Co/ZSM-5.

Effects of CO2 on the deactivation behaviors of Co/Al2O3 and Co/SiO2 in CO hydrogenation to hydrocarbons

Different deactivation behaviors of the prototype Co/γ-Al₂O₃ (CoAl) and Co/SiO₂ (CoSi) catalysts under an excess CO₂ environment were investigated in terms of the surface oxidation and aggregation of cobalt crystallites for the Fischer–Tropsch Synthesis (FTS) reaction.

Perspectives on zeolite-encapsulated metal nanoparticles and their applications in catalysis

Recent strategies for the design of zeolites with unusual architectures and porosities offer many opportunities for the encapsulation of catalysts.

Effect of SiO2/Al2O3 ratio on the activities of CoRu/ZSM-5 Fischer–Tropsch synthesis catalysts

Interaction between Co and framework defects decreases the activity of the ZSM-5-supported CoRu catalyst in the FTS reaction.

Catalysis engineering of bifunctional solids for the one-step synthesis of liquid fuels from syngas: a review

The combination of acidic zeolites and Fischer–Tropsch synthesis (FTS) catalysts for one-step production of liquid fuels from syngas is critically reviewed.