Fischer-Tropsch Research Articles

Green and designable deep eutectic solvents for extraction separation of oxygenated compounds in Fischer-Tropsch oil products: Hydrogen bond descriptors and structure–activity study

In this work, choline fluoride, choline chloride, and 2-fluoroethyl-trimethylammonium bromide containing –F, –Cl, and –Br structures were used as hydrogen bond receptors. Acetamide, urea, trifluoroacetamide, xylitol, ethylene glycol, malonic acid and lactic acid containing –HN2, –COOH, –OH, and –F structures were used as hydrogen bond donors. We constructed functional deep eutectic solvents rich in hydrogen bond donors and acceptors while providing alcohol hydrogen bond attraction sites and aldehyde and ketone hydrogen bond attraction sites. The efficient separation and enrichment of trace alcohols, aldehydes, and ketones in Fischer-Tropsch (F-T) oil products were achieved through hydrogen bond interaction. The mechanism of selective extraction of different types of oxygenated compounds by functionalized deep eutectic solvents was revealed, and the linear relationship among structure, hydrogen bond descriptor, and extraction performance was clarified through quantum chemistry calculations. Further, liquid–liquid extraction was used to extract and separate the oxygenated compounds from high-temperature F-T oil products using the synthesized functional deep eutectic solvent. The experimental results showed that propanol, butyraldehyde, and methylethylketone could be extracted simultaneously and efficiently, and the solvent effects were consistent with the results of quantum chemistry calculation. The excellent extraction and separation effects were due to the large number of hydrogen bonds and oxyphilic atomic forces of deep eutectic solvents. The modern solvent was reasonably designed, which is significant for extracting different oxygenated compounds from high-temperature F-T oil products.

Elucidation of Organometallic Reaction Mechanisms by a China-Germany Team.

This invited Team Profile was created by Jiaxiang Chu at the University of Chinese Academy of Sciences (China) and Dominik Munz at Saarland University (Germany). They recently reported isocyanide homologation mediated by aluminium(I) as a Fischer-Tropsch model reaction. Up to five molecules were coupled, and the step-by-step mechanism was elucidated. Combined mechanistic/computational work provided evidence that carbenes are the key intermediates during this process. "Evidence for Carbene Intermediates in Isocyanide Homologation by Aluminium(I)", C. J. Zhang, F. Dankert, Z. A. Jiang, B. L. Wang, D. Munz, J. X. Chu, Angew. Chem. Int. Ed. 2023, 62, e202307352.

Elucidation of Organometallic Reaction Mechanisms by a China–Germany Team

AbstractThis invited Team Profile was created by Jiaxiang Chu at the University of Chinese Academy of Sciences (China) and Dominik Munz at Saarland University (Germany). They recently reported isocyanide homologation mediated by aluminium(I) as a Fischer–Tropsch model reaction. Up to five molecules were coupled, and the step‐by‐step mechanism was elucidated. Combined mechanistic/computational work provided evidence that carbenes are the key intermediates during this process. “Evidence for Carbene Intermediates in Isocyanide Homologation by Aluminium(I)”, C. J. Zhang, F. Dankert, Z. A. Jiang, B. L. Wang, D. Munz, J. X. Chu, Angew. Chem. Int. Ed. 2023, 62, e202307352.

Carbon abatement costs for renewable fuels in hard-to-abate transport sectors

Renewable fuels can help to reduce carbon emissions from transportation. To inform planning decisions, this paper estimates carbon abatement costs of replacing fossil fuels with renewable hydrogen, ammonia, or Fischer–Tropsch e-fuel in Norwegian freight transport across long-haul trucking, short-sea shipping, and medium-haul aviation. We do this by applying a holistic cost model of renewable fuel value chains. We compare abatement costs across transport sectors and analyze how policy interventions along the value chains – such as carbon pricing, subsidies, and de-risking policies – impact carbon abatement costs. We estimate abatement costs of 793–1,598 €/tCO2 in 2020 and -11–675 €/tCO2 in 2050, depending on the electricity source, transport sector, and type of fuel. A 1 €/kg reduction in the cost of hydrogen - e.g. through a subsidy - lowers present-day carbon abatement cost by 95 €/tCO2 for hydrogen-powered trucking, 133 €/tCO2 for e-fuel-powered shipping, and 143 €/tCO2 for e-fuel-powered aviation. We further show that reductions in the weighted average cost of capital materially decrease abatement cost, particularly for renewable hydrogen due to its relative capital intensity.

Electrochemical syngas production over Au/SrTiO3 and Fischer–Tropsch synthesis chemistry for long-chain hydrocarbons

Syngas (a mixture of CO and H2) has been utilized in industrial settings for the production of liquid fuels through Fischer–Tropsch (F-T) synthesis. The conventional methods of producing syngas involve energy-intensive processes utilizing coal, natural gas, or biomass. However, in order to promote more environmentally friendly practices, electrochemistry has emerged as an alternative approach. In this study, we demonstrate that syngas can be efficiently produced through electrochemical (EC) CO2 conversion using Au-loaded perovskite strontium titanate (SrTiO3) as a catalyst. By manipulating various parameters such as overlayer Au thickness, applied potential, electrolyte type, and concentration, we can easily control the ratio of CO to H2. Moreover, our findings reveal that electrochemistry can directly initiate the minor channel of the F-T synthesis process. We also observe the occurrence of the EC F-T process in CO-saturated electrolyte, where CO molecules directly adsorb and interact with surface H to generate hydrocarbons. The analysis of the Anderson-Schulz-Flory equation demonstrates a strong linear relationship, confirming that the EC F-T synthesis follows the conventional F-T synthesis mechanism. This novel demonstration not only offers valuable insights into the development of EC syngas production but also enhances our understanding of the mechanism behind the formation of C2+ hydrocarbon products.

Study fischer-tropsch synthesis

This work was to evaluate the catalytic properties Ru/Cobalt/SBA-15 catalyst for Fischer-Tropsch synthesis (FTS). The molecular sieve SBA-15 synthesized by hydrothermal method with rice husk ashes (RHA) and with tetraethyl orthosilicate (TEOS). The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalysts were carried out to evaluate the catalysts activities and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO : H2 molar ratio of 1 : 2. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present under the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. By RTP results was found the ranges of temperature reduction typical of iron oxides phases. Fischer-Tropsch synthesis activity and C5+hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. The most interesting fact to be pointed out is that the use of this catalytic system for the catalyst prepared with alternative source of silica and cheap (rice hull ash) showed high selectivity in liquid products, that is, in hydrocarbons with C5+ (88.2% w/w ), higher than the catalyst prepared with conventional silica source.

Nickel oxide/copper nanocluster anchored in carbon-nitride nanosheets realizing ultrahigh stability and broad potential range for zero-gap membrane flow reactor towards CO2-into-CO electroreduction

CO2 electrochemical reduction is a sustainable approach to achieve chemical fixation of CO2 and storage of renewable energy. However, the catalyst which has the ability of mediating CO2 to a single product with a relatively high current density is highly demand. Herein, we reported a metallic nitrogen-carbon catalyst based on two kinds of metal phthalocyanines by a facile synthesis method. The synergistic effect of Cu and Ni and the active sites of nickel oxide/copper nanocluster endow the catalyst excellent performance towards CO2-into-CO electroreduction. Typically, the Cu-Ni bimetallic catalyst achieves high selectivity (85.2 %) at positive potential (−0.72 VRHE), with the stability of current density and product selectivity beyond 72 h. The volume ratio of CO/H2 can be effectively tuned (from 2:1, 1:1 to 1:2) by controlling the electrolysis potential, which is promising for synthesis gas in the Fischer-Tropsch reactions and methanol synthesis. Furthermore, the advantages are further amplified by applying it to zero-gap membrane flow reactor, which can enhance the selectivity over 90 % at a broad potential range (−2.5 ∼ −2.7 V) and achieve an current density of 9-fold of H-type cell. Our work proves a way for optimizing the CO2 electrocatalyst and electrolyzers.

Mechanistic proposal for the conversion of syngas to light alkanes in Zn-ZSM-5 zeolite linking theoretical calculations to experimental characterizations

The direct syngas conversion to olefins, aromatics and other hydrocarbons has attracted increasing attention while unraveling the complex reaction mechanism is of great challenge. It was recently demonstrated that zinc-exchanged zeolites could selectively convert syngas to alkanes, particular ethane, and [Zn–O–Zn] motif is likely the intrinsic active site. The underlying reaction network however remains ambiguous. Herein, we proposed a reaction mechanism for the direct conversion of syngas to light alkanes including methane and ethane using density functional theory calculations in periodic [Zn–O–Zn]-ZSM-5 zeolite model. The evolution of syngas to ethane follows the sequence of CO → CH2O → CH2CO → CH3CHO → C2H6. The activation of CO to formaldehyde initiates the reaction. The [Zn–O–Zn] site can readily be reduced by CO to [Zn–Zn] site, which either inserts aldehydes to form [Zn–O-CnH2n-Zn] motif for chain propagation to higher aldehydes, or converts aldehydes to alkanes for chain termination. Ketene is the first intermediate after the C–C bond coupling between [Zn–O–CH2–Zn] and CO. Both the structures and the evolution sequence of the involved intermediates in the proposal (formyl, methylene, acetyl, ethyl) coincide quite well with experimentally quasi in-situ characterized results. The proposed reaction network consisting of initiation, propagation and termination sub-cycles unifies the formation pathway of methane, ethane, and higher alkanes, and bears some resemblance to the Fischer-Tropsch synthesis for syngas conversion. This theoretical work thus further vindicates the critical role of [Zn–O–Zn] site and may proffer some implications to tailor alkane selectivity in metal-exchanged zeolites for syngas conversion.

Operando characterisation of the products of Fischer-Tropsch synthesis in a fixed-bed reactor studied by magnetic resonance

Operando measurement of catalyst performance presents many difficulties as it is necessary to obtain measurements at reaction temperature and pressure and also at relevant length scales of multiple pellets to replicate the pellet-scale mass transport. Non-invasive measurement under such conditions is challenging. In this study we have developed an NMR/MRI compatible reactor that is of industrially-relevant scale and can operate at typical conditions for Fischer-Tropsch synthesis (FTS). The pilot-scale fixed-bed reactor (20 mm i.d.) used for FTS is operated at 220 °C and 37 bar and is packed with 1 wt % Ru/TiO2 catalyst pellets. Multiple magnetic resonance techniques have been developed and applied to achieve quantitative characterisation of product species including hydrocarbons, water, oxygenates and branched alkanes in pores. In addition to spatially-resolved measurements of molecular diffusion coefficients of the product species from which the carbon chain length of the saturated hydrocarbons can be determined, preliminary estimates of the relative amount of oxygenate and water species and branched saturated hydrocarbons present within the pore space of the catalyst are also determined using non spatially-resolved two-dimensional 1H T1-chemical shift and two-dimensional 1H double quantum filtered correlated spectroscopy (DQF-COSY), respectively. The concentrations of water and oxygenates detected inside the pores of catalyst pellets decrease when the feed H2/CO ratio decreases. The amount and extent of branching of saturated hydrocarbon species is observed to be higher than for the effluent wax product, most likely due to the effect of mass transfer limitation within the reactor. This work demonstrates that a toolbox of operando magnetic resonance techniques is available to characterise different product species of FTS from within catalyst pellets. The information provided by these techniques can give insight into how both catalyst and reactor can be optimised.

Unlocking long-chain hydrocarbons (C2–7) via direct electrochemical CO2 and CO reduction on balanced Au/Ni electrodes

Electrochemical (EC) CO2 reduction method has been widely used as a green energy and environmental solution strategy. The use of Au/Ni electrodes was introduced to showcase a new concept of the direct EC Fischer-Tropsch (dEC F-T) synthesis pathway. This pathway involves the combination of electrodes that produce H2 and CO (syngas) during electrochemical CO2 reduction. The introduction of Au on the Ni electrode surface led to an increase in CO production and a gradual decrease in H2 production. When the interface was balanced, a pronounced F-T synthesis pathway was observed, resulting in the production of a series of hydrocarbons (CnH2n and CnH2n+2, n = 2–7). The dEC F-T synthesis was evaluated under different conditions, including electrolytes, concentrations, metal supports (Co and Fe), various overlayer metals (Ag and Cu), light irradiation, and isotope effects. The process was elucidated through surface C−C coupling polymerization reactions based on Anderson-Schulz-Flory weight distribution analysis. Additionally, the F-T synthesis was demonstrated through EC CO reduction via direct CO and H adsorption. The dEC F-T path provides a novel strategy for energy and environment by producing high-value long-chain hydrocarbons.

Fischer‐Tropsch Synthesis by a Cobalt‐Based Carbon Aerogel Catalyst

AbstractCarbon aerogel (CA) as a novel catalyst support in Fischer‐Tropsch synthesis (FTS) was synthesized by polymerization of a resorcinol‐formaldehyde (RF) precursor through an ambient pressure drying route. The cobalt‐doped CA was synthesized by three main strategies: (a) impregnation of the metal precursor on the CA (Co‐CA‐I), (b) carbonization of cobalt‐doped organic RF aerogel (Co‐CA‐II), and (c) addition of the cobalt precursor to the RF mixture (Co‐CA‐III). The pores and cobalt particle size increased in the order of Co‐CA‐I > Co‐CA‐II > Co‐CA‐III and cobalt particles wrapped between the graphite layers when cobalt was added to the RF mixture. The CA as the catalyst support presented high CO conversion and high stability under FTS conditions. The CH4 selectivity increased by reducing the size of the cobalt particles. Hydrogen spillover from the support to metallic particles was observed in the case of Co‐CA‐I and Co‐CA‐III catalysts. This phenomenon improved the reducibility and also resulted in higher hydrogenated products being produced.

Comparative Life Cycle Assessment of Alternative Marine Fuels

With the stricter rules introduced by the policymakers in maritime transportation, harmful emissions are aimed to be mitigated. Consequently, studies on alternative fuels have emerged, and different methods had adopted to evaluate fuel choices. Within this context, a well-to-wake life cycle assessment method is used to determine the environmental impacts of the fuel options. Included fuels in the study are ammonia, biodiesel, Dimethyl ether, electro Fischer Tropsch diesel fuel, electro methanol, Fischer Tropsch diesel fuel, hydrogen, liquefied natural gas, liquefied petroleum gas, marine diesel oil, marine gas oil, marine bio-oil, methanol, pyrolysis oil, renewable diesel, straight vegetable oil, and ultra-low sulfur heavy fuel oil. The paper aims to evaluate the fuels according to the 2050 strategy of the International Maritime Organization. Hence, black carbon, carbon monoxide, carbon dioxide, nitrous oxide, nitrogen oxide, sulfur oxide, particulate matter, methane, and volatile organic compounds are considered emissions. During the study, an ocean tanker model available in the GREET Model 2022 was used for life cycle inventory analysis, and life cycle assessment was conducted by Environmental Footprint Method 3.0, which is included in the OpenLCA. The assessment was carried out according to climate change, acidification, freshwater ecotoxicity, marine eutrophication, terrestrial eutrophication, non-cancer human toxicity, particulate matter, and photochemical ozone formation criteria. The results show that out of eight criteria, marine bio-oil became the most dominant choice due to the consumption of CO2 and methane while producing and low emission generation during combustion.

Biomass gasification: Sub-pilot operation of >600 h with extensive tar cracking property and high purity syngas production at H2:CO ratio ∼2 using moving bed redox looping technology

Commercializing biomass-based technologies as an alternative to fossil fuels is necessary for a sustainable future. This study proposes a robust Biomass to Syngas (BTS) chemical looping system to gasify biomass into syngas for a range of downstream applications, with focus on liquid fuel production. The system has been demonstrated on a sub-pilot scale cumulatively for over 600 h, proving the technology's commercial viability. Pelletized corn cob, woody pellets, and unpelletized loose corn cob, were successfully tested, proving the robusticity of the process to handle untreated biomass with batch variation. Tar analysis shows that moving bed reducer can reduce the tar concentration to 0.5 g/m3, owing to uniform residence time, high temperature, and catalytic activity of oxygen carrier, while injection of steam as an enhancer gas increases carbon conversion by char gasification. A variable syngas quality with an H2/CO ratio of ∼2 and a syngas purity greater >70% was achieved, making this syngas suitable for the generation of liquid fuels via Fischer-Tropsch synthesis. The biomass requirement for a chemical looping system decreases by 13.9% over the conventional biomass gasifier for generating the same amount of liquid fuels. Heat integration suggests integrating biomass drying with the combustor exhaust air for process authothermicity.

О МЕХАНИЗМАХ ОБРАЗОВАНИЯ НАНОСТРУКТУРНЫХ ЭЛЕКТРОЛИТИЧЕСКИХ ПОКРЫТИЙ Fe-Ni, Co-Mn, Ni-Cr С ФУНКЦИОНАЛЬНЫМИ СВОЙСТВАМИ

The evolution of modern industry is impossible without the development of new materials and technologies. Nanostructured coatings, in particular electrolytic coatings, are among the most demanded in mechanical engineering. The purpose of this work was to study the different mechanisms of obtaining Fe-Ni, CoMn, Ni-Cr galvanic alloys and their relationship with the specified universal physical and mechanical properties. Fe-Ni alloy is characterized by high microhardness and corrosion resistance in sea water, low cold brittleness; Co-Mn – by a specified phase composition (α-Co >> α-Mn, amorphous and metastable phase Co(OH)2); Ni-Cr – by high coating microhardness, specified phase composition. The main methods of production: high-frequency alternating current for Fe-Ni and Co-Mn alloys; introduction of a special additive (carbamide or H-acid) for Ni-Cr alloy. The main mechanisms are: Fe-Ni due to phase transition α-Fe ε-Fe; Co-Mn by means of high-frequency alternating current and carbamide addition, providing a specified phase composition; Ni-Cr by means of stationary method of addition of H-acid (high-chromium alloy of 68 mass percent of Cr) and carbamide (low-chromium alloy of 25 mass percent of Cr). Recommended uses for electroplating: Fe-Ni – for protection of oil and gas production equipment in the Arctic; CoMn – in modulation systems and as a nanocatalyst in the Fischer-Tropsch synthesis reaction; Ni-Cr – for corrosion-resistant protective coatings in petrochemistry and for resistive elements.

Direct hydrogenation of CO2 to aromatics via Fischer-Tropsch route over tandem K-Fe/Al2O3+H-ZSM-5 catalysts: Influence of zeolite properties

Direct hydrogenation of CO2 to valuable aromatics using multifunctional catalysts is an attractive technology to produce low-carbon footprint chemicals. In this work, the relevant zeolite parameters driving the formation of total and BTEX aromatics from CO2 and H2 on tandem K-Fe/γ-Al2O3+H-ZSM-5 catalysts following the Fischer-Tropsch (FT)-mediated route were investigated. To this end, a set of H-ZSM-5 zeolites covering a wide range of physicochemical properties (density of Brønsted and Lewis acid sites, external acidity, crystallite size, and mesoporosity) was used, characterized by different techniques (ICP-OES, XRD, N2 physisorption, FTIR-pyridine, FTIR-2,6,-di-tert-butyl pyridine, XPS, 27Al MAS NMR, and electron microscopy), and evaluated in CO2 hydrogenation at 400 °C, 30 bar, H2/CO2 = 3.1, and GHSV of 4700 mL/(gFe-cat·h). At these conditions, high and stable CO2 conversions of 50 – 55% and low CO selectivity of ca. 10% were obtained for the Fe-based and tandem catalysts. The density and, to a certain extent, the strength of Brønsted acid sites were found the main parameters determining the selectivity of aromatics, reaching initial (TOS = 1.5 h) values of about 79% and 40% in liquid (C5+) and total hydrocarbons, respectively, for the catalyst based on the most acidic zeolite. Lewis acid sites associated to extraframework Al species (EFAL), by contrast, did not appear to play a relevant role in our conditions. Moreover, although a positive effect of the total amount and strength of Brønsted acid sites on the selectivity to the most valuable BTEX aromatics was inferred from our results, the external Brønsted acidity was the most influential factor in this case. Hence, a remarkable BTEX selectivity of 75% in aromatics was achieved for the zeolite previously submitted to a surface-passivation treatment by silylation.

Maximizing Liquid Fuel Production from Reformed Biogas by Kinetic Studies and Optimization of Fischer–Tropsch Reactions

In the current work, the operating conditions for the Fischer–Tropsch process were optimized using experimental testing, kinetic modelling, simulation, and optimization. The experiments were carried out using a Ce-Co/SiO2 catalyst to examine how operating parameters affected the conversion of CO and product selectivity. A power-law kinetic model was used to represent the reaction rates in a mathematical model that was created to replicate the Fischer–Tropsch synthesis (FTS). It was decided to estimate the kinetic parameters using a genetic optimization technique. The developed model was validated for a range of operating conditions, including a temperature range of 200–240 °C, a pressure range of 5–25 bar, a H2/CO ratio of 0.5–4, and a space velocity range of 1000–5000 mL/gcat·h. The mean absolute relative error (MARE) between the experimental and predicted results was found to be 11.7%, indicating good agreement between the experimental data and the predicted results obtained by the mathematical model. Optimization was applied to maximize the production of liquid biofuels (C5+). The maximum C5+ selectivity was 91.66, achieved at an operating temperature of 200 °C, reactor total pressure of 6.29 bar, space velocity of 1529.58 mL/gcat·h, and a H2/CO feed ratio of 3.96. The practical implications of the present study are maximizing liquid biofuel production from biomass and municipal solid waste (MSW) as a renewable energy source to meet energy requirements, reducing greenhouse gas emissions, and waste management.

The oscillating Fischer-Tropsch reaction.

The mechanistic steps that underlie the formation of higher hydrocarbons in catalytic carbon monoxide (CO) hydrogenation at atmospheric pressure over cobalt-based catalysts (Fischer-Tropsch synthesis) have remained poorly understood. We reveal nonisothermal rate-and-selectivity oscillations that are self-sustained over extended periods of time (>24 hours) for a cobalt/cerium oxide catalyst with an atomic ratio of cobalt to cerium of 2:1 (Co2Ce1) at 220°C and equal partial pressures of the reactants. A microkinetic mechanism was used to generate rate-and-selectivity oscillations through forced temperature oscillations. Experimental and theoretical oscillations were in good agreement over an extended range of reactant pressure ratios. Additionally, phase portraits for hydrocarbon production were constructed that support the thermokinetic origin of our rate-and-selectivity oscillations.

Study on spray and combustion characteristics of Fischer-Tropsch diesel/biodiesel blends in a constant volume chamber

Fischer-Tropsch (F-T) diesel synthesized from coal is a promising alternate fuel for diesel engines. Because F-T diesel has low viscosity and does not contain oxygen, biodiesel is added to F-T diesel in this study to increase the viscosity and oxygen content of F-T diesel. In this study, the effects of adding different proportions of biodiesel (20% and 50% in volume) to F-T diesel on spray and combustion characteristics are investigated using constant volume chamber (CVC). The experimental results show that among petro-diesel, F-T diesel, and biodiesel, F-T diesel has the best evaporation performance and biodiesel has the worst. When biodiesel is added to F-T diesel, the evaporative property of the fuel becomes worse. At the ambient temperature of 773K, the liquid spray projected area of FB20 and FB50 increase by 28.9% and 64.9%, respectively, compared with FT100. Compared with petro-diesel, F-T diesel and biodiesel have shorter ignition delay and flame lift-off length. In addition, the flame temperature and KL of biodiesel are significantly lower. After blending biodiesel with F-T diesel, the ignition delay and flame lift-off length gradually increase, which will be beneficial for air fuel mixing. In addition, adding biodiesel will lower the flame temperature and KL. Compared with F100, the KL of FB20 and FB50 decrease by 7.4% and 20.2%, respectively.

Probabilistic assessment of the safety profile of the Fischer–Tropsch process with a supercritical solvent

AbstractInherent safety assessment during the design stage of chemical processes is typically conducted based on average values for design parameters. Under those conditions, the single‐point deterministic process performance assessment may be affected by the phenomenon known as the ‘flaw of averages’ in the presence of irreducible sources of uncertainty (performance evaluated at average conditions does not represent average performance). In this work, an inherent process safety assessment developed under a probabilistic formulation is presented. An evaluation of the proposed approach is performed in the case of a gas‐to‐liquid process system using a supercritical solvent for Fischer–Tropsch reactor systems. The pertinent uncertainty analysis is carried out using Monte Carlo simulation techniques to account for the propagation of uncertainty through the inherent process safety model and the derivation of probability distribution profiles for the associated metrics, thus statistically characterizing ranges of potential performance outcomes. The response variables were the autothermal reactor and the syngas flows. The results show that the input variables associated to the autothermal flow potentially generate the most hazardous conditions for the process. The results also show how the metrics are affected when uncertainty is explicitly taken into account at the design stage of the process, offering a more nuanced assessment and characterization of the inherent process safety profile.

Bayesian optimization of multiscale kernel principal component analysis and its application to model Gas-to-liquid (GTL) process data

Kernel methods map the data from original space into a higher-dimensional space in which linear methods are applied. In many applications, the inverse mapping is also important, and the pre-image of a feature vector must be found in the original space. Kernel principal component analysis (KPCA) based kernel density estimation (KDE) has been developed to solve this problem. However, the performance of the KPCA technique greatly depends on the choice of some parameters which can lead to poor modeling performance when these parameters are not well identified. Thus, fully Bayesian optimization KPCA (BOKPCA) is proposed to enhance the performance of the KPCA model. BOKPCA method aims to automatically select the best parameters of the KPCA model. Generally, kernel methods struggle to handle nonlinear data contaminated with high levels of noise. This is because the noise affects every principal component, making it challenging to mitigate its influence during the reconstruction step. Consequently, to further enhance the ability of KPCA and BOKPCA models, we propose to integrate multi-scale filtering with these two models. The efficiency of the proposed methods are evaluated using a simulated nonlinear process and real data generated from a bench-scale Fischer–Tropsch (FT) process.