Hydrocracking Research Articles

Catalyst Accessibility and Acidity in the Hydrocracking of HDPE: A Comparative Study of H-USY, H-ZSM-5, and MCM-41 Modified with Ga and Al.

Plastic pollution is a critical environmental issue due to the widespread use of plastic materials and their long degradation time. Hydrocracking (HDC) offers a promising solution to manage plastic waste by converting it into valuable products, namely chemicals or fuels. This work aims to investigates the effect of catalyst accessibility and acidity on the HDC reaction of high density polyethylene (HDPE). Therefore, a variety of materials with significant differences in both textural and acidic properties were tested as catalysts. These include H-USY and H-ZSM.5 zeolites with various Si/Al molar ratios (H-USY: Si/Al = 2.9, 15, 30 and 40; H-ZSM-5: Si/Al = 11.5, 40, 500) and mesostructured MCM-41 materials modified with Ga and Al, also with different Si/metal ratios (Si/Al = 16 and 30; Si/Ga = 63 and 82). Thermogravimetric analysis under hydrogen atmosphere was used as a preliminary screening tool to evaluate the potential of the various catalysts for this application in terms of energy requirements. In addition, batch autoclave reactor experiments (T = 300 °C, PH2 = 20 bar, t = 60 min) were conducted to obtain further information on conversion, product yields and product distribution for the most promising systems. The results show that the catalytic performance in HDPE hydrocracking is determined by a balance between the acidity of the catalyst and its structural accessibility. Accordingly, for catalyst series where the structural and textural properties do not vary with the Si/Al ratio, there is a clear correlation of the HDPE degradation temperature and of the HDPE conversion with the Si/metal ratio (which relates to the acidic properties). In contrast, for catalyst series where the structural and textural properties vary with the Si/Al ratio, no consistent trend is observed and the catalytic performance is determined by a balance between the acidic and textural properties. The product distribution was also found to be influenced by the physical and chemical properties of the catalyst. Catalysts with strong acidity and smaller pores were observed to favor the formation of lighter hydrocarbons. In addition to the textural and acidic properties of the catalyst, the role of coke formation should not be neglected to ensure a comprehensive analysis of the catalytic performance.

Process design and analysis of a net-zero carbon emissions hydrocracking unit integrating co-processing technique with green hydrogen and electricity

To mitigate carbon emissions from refineries, it is feasible to integrate established technologies such as green hydrogen, green electricity, bio-gas, and bio-oil co-processing into hydrocracking (HC) units. To clarify the contribution of these technologies to carbon reduction in HC units, three scenarios are proposed: Scenario 1 involves coupling green hydrogen and green electricity with HC units; Scenario 2 builds upon Scenario 1 by incorporating bio-gas; and Scenario 3 integrates co-processing technology into Scenario 1. The carbon emissions of the three scenarios are analyzed and compared based on the life cycle concept. The results show that for traditional HC units, carbon emissions at the input reaches 876.98 t/h, with vacuum gas oil and hydrogen constituting the majority at 96.7%. Under Scenario 1, carbon emissions at the input of the HC unit are reduced by 45.44 t/h, whereas Scenario 2 yields a reduction of 52.61 t/h. Remarkably, Scenario 3 achieves a substantial reduction of 272.56 t/h. The sensitivity analysis results indicate that carbon emissions are most sensitive to the bio-oil co-processing ratio and least sensitive to the penetration ratio of green electricity. Therefore, the adoption of co-processing technology is deemed most effective to reduce carbon emissions from HC units.

The effect of recycle stream on slurry-phase hydrocracking of vacuum residue: An experimental and modeling approach

The effect of the recycle stream on slurry-phase hydrocracking (HCK) of vacuum residue was examined using a continuous bench-scale unit with the aim of attaining process optimization. This was achieved through a model-based approach that links experimental investigations, kinetic modeling, and model-based optimization. The experiments were conducted at various reaction temperatures, liquid hourly space velocity of fresh feed (LHSVFF) and recycle ratios at a pressure of 160 bar, with the fresh feed containing 1000 wt. ppm of molybdenum. The HCK kinetic model was modified to incorporate the recycling effects and accurately predict the experimental data. The adapted model confirmed that the unconverted residue in recycle operating mode (ROM) became more refractory. By implementing the modified kinetic model in a dynamic Simulink model, the prediction accuracy of RES conversions and product yields can be improved by up to 25.1 wt.% in the case of the lowest conversion. A sensitivity analysis using the dynamic model showed that the temperature exerted a greater impact on the RES conversion and recycle ratio in ROM. An operational stability index was also proposed to prevent operation failure in ROM. Finally, an optimal operating condition from the parametric study was found to meet several process goals simultaneously.

Hydrocracking of hydrotreated light cycle oil for optimizing BTEX production: a simple kinetic model

Abstract The effect of the experimental conditions on the hydrocracking (HCK) of a hydrotreated light cycle oil (HDT LCO) was studied in this work. The catalyst tested was a 50/50 weight mixture of nickel-molybdenum-phosphorous on alumina (NiMo/Al2O3) and a commercial ZSM5 zeolite (HCK 50/50). The experimental conditions tested were 340, 350, 360, and 370 °C; 7.5 MPa; 0.9, 1.2, 1.5, and 1.8 h−1 LHSV, and H2/HC of 752 m3/m3. Two phases: gas and liquid, were obtained as HDK products. The gas phase consisted mostly of C1–C5 paraffins, iso-paraffins, and olefins. The liquid phase was characterized by GC-PIONA and was distributed in lumps as follows: NAPA by C11 to C13-naphthalenes; TET by C11 to C13-tetralins; IND by C9 to C13-indanes and indenes; AKB by C9 to C13-alkylbenzenes; BTEX by benzene, toluene, ethylbenzene, and xylenes; NAPE by C9 to C13-naphthenes; and PIP by C3 to C14 paraffin, iso-paraffin, and olefin type hydrocarbons. Using this classification, the results showed that increments in temperature and decrements in LHSV produced increments in the formation of gases, PIP, BTEX, and NAPE. At the same conditions, AKB, TET, NAPA, and IND decreased sharply. TET and NAPA derivatives were no longer present at high temperatures (360–370 °C). It seemed to be a limit of the BTEX formation directly related to the TET and IND presence, and it did not seem to depend on the transalkylation process of AKB hydrocarbons. Instead, AKB hydrocarbons were directly correlated to NAPE hydrocarbon formation by hydrogenation. A kinetic model was prepared. The model presented correlation coefficients higher than 98 %. The kinetic model that was made predicted that neither increasing the temperature nor lowering the LHSV would improve the BTEX formation when departing from this feedstock.

Hydro-co-processing of a jatropha oil and gas oil blend with a sulfided Ni–W catalyst supported on mesostructured materials Al(x)-SBA-15 type for cleaner hybrid diesel production: Effect of the Al/Si molar ratio

Obtaining cleaner hybrid diesel fractions by hydro-co-processing vegetable oil and gas oil blends requires tailoring intrinsic properties (metal content and acidity) of a solid catalyst. Such catalyst must promote the hydrodesulfurization (HDS), hydrodeoxygenation (HDO), and hydrocracking (HCK) reactions. In that sense, the present research work reports the synthesis (sol–gel and hydrothermal), characterization (N2 physisorption, XRD, HR-TEM, 27Al-MAS-NMR, Pyridine-FTIR, and RAMAN spectroscopy), and catalytic evaluation (6 MPa of H2 initial pressure, 360 °C, and 4 h) for Ni–W/Al(x)-SBA-15 sulfided catalysts during the hydroprocessing of a 20 vol% of Jatropha Curcas L. oil blend with a mixed gas oil (50 vol% LGO and 50 vol% HGO). Metal content of the catalysts was fixed at 2.5 wt% of NiO and 15 wt% of WO3, meanwhile, the Al/Si (x) molar ratio was adjusted in 0.1, 0.05, 0.033, 0.025, and 0.0 to study the effect of aluminum (Al) content during hydroprocessing. Liquid products were analyzed by FTIR, 1H NMR, ESI-MS, Simulated Distillation (ASTM D2887) and ASTM D4294 for S content. The effect of Al incorporation was mainly observed in the hydrotreating reactions (HDO and HDS) rather than HCK reactions. Intermediate Al/Si molar ratios (0.05, and 0.03) promoted the highest sulfur removal of about 13.1 % compared with the 10.7 % and 5.6 % for 0.1 and 0.025 Al/Si molar ratios, respectively. In addition, the highest content of Brønsted (0.05 mmol g−1) and Lewis (1.45 mmol g−1) acid sites was observed for the Ni–W/Al(0.05)-SBA-15 catalyst. Regarding HDO activity, it was the highest (57.3 %) for Ni–W/Al(0.1)-SBA-15 catalyst, and the lowest (30.9 %) for Ni–W/Al(0.025)-SBA-15, and Ni–W/Al(0.0)-SBA.15 sulfided catalysts. Finally, by comparing HDS and HCK activities of Ni–W/Al(0.05)-SBA-15 and Ni–W/Al(0.0)-SBA-15 sulfided catalysts, it was observed that HDS decreased 7.5 % and HCK increased 2.4 % when no Al was incorporated.

Synergistic shape selectivity of H-Beta and H-ZSM-5 for Xylene-rich BTX production by hydrocracking of heavy-aromatic compounds

Catalytic hydroconversion of C10+ heavy aromatics (C10+ Aro) from an aromatic complex was studied to produce benzene, toluene, and xylenes (BTX), rich in xylenes. Two catalytic schemes, direct hydrocracking (HDC) and hydrotreating (HDT) followed by HDC, were explored. The Mo2C/γ-Al2O3 catalyst exhibits excellent selectivity for mono-aromatics and catalytic stability in the HDT of C10+ Aro. HDC catalysts containing BZ (H-Beta/H-ZSM-5 = 9/1 weight ratio) exhibited a significantly enhanced yield of BTX but significantly reduced the formation of alkylbenzenes (other than BTX) and heavy aromatic residues compared to the HDC catalyst without H-ZSM-5. H-ZSM-5 with smaller pore size and higher Brönsted acidity than H-Beta promoted dealkylation of alkylbenzenes into BTX while limiting heavy residue formation. HDC of HDT-C10+ Aro over NiMo/BZ catalyst resulted in BTX and BTX + C9 Aro yields as high as 47.7 and 61.1 wt%, respectively, which were significantly higher than those obtained from direct HDC of C10+ Aro (44.4 and 53.8 wt%). Unlike model tetralin HDC, the BTX distribution was in the order X > T > B from the HDC of HDTC10+ Aro. Transalkylation reactions between benzene/toluene and tetramethylbenzenes (in C10+ Aro) have been suggested as possible mechanisms for the formation of xylene-rich BTX.

Effect of Zn Contents of W/Zn-Beta Catalysts on Their Catalytic Performance in the Selective Hydrocracking of Tetrahydronaphthalene into Benzene, Toluene, and Xylene

Selective hydrocracking (HDC) of tetrahydronaphthalene (THN) into light aromatic hydrocarbons, such as benzene (B), toluene (T), and xylene (X), was performed over bifunctional catalysts with different ZnO contents (W/Zn-Beta) at 400 °C and 6 MPa. In this work, the change of catalytic performance of the bifunctional catalysts with different ZnO contents in selective HDC of THN and the nine-lump reaction kinetic model was investigated. It was found for the first time that ZnO can not only effectively regulate the acid properties of Beta zeolite but also react with WO3 to form non-active ZnWO4 crystals, resulting in low HDC activity of the catalyst. At low ZnO contents of the catalyst (<1 wt %), as the interaction of ZnO–Beta is stronger than that of WO3–Beta, the interaction of ZnO–Beta would replace the interaction of WO3–Beta, leading to the agglomeration of WO3 and the dispersions of WO3 on Beta zeolite decrease. As a result, WO3 would be easily reduced to WS2, and the BTX selectivity would increase. At high ZnO contents of the catalyst (≥1 wt %), the strong acid sites of Beta zeolite would be covered by ZnO. In addition, the excess ZnO would react with WO3 to form non-active ZnWO4 crystals, and the BTX selectivity would decrease. The W(25)/Zn(1)-Beta-40 catalyst exhibited maximal BTX selectivity (45 wt %) at 94% THN conversion. The kinetic study further indicated that with the increase of ZnO contents, the ratio of formation reaction rate of BTX to the over-HDC rate of BTX increases first and then decreases, and the reaction path selectivity of THN isomerization increases.

Highly active and stable CoWS2 catalysts in slurry phase hydrocracking of vacuum residue: XAFS studies

The bimetallic CoWS2 catalysts were prepared in situ during the slurry phase hydrocracking (HCK) of vacuum residue (VR) using W(CO)6 and Co-octoate as oil soluble precursors to investigate the promotional effect of Co promoters on the dispersed WS2 catalyst for the VR HCK. The morphologies and structural properties of dispersed catalysts were characterized by transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). The bimetallic CoWS2 catalyst was observed to form well-dispersed monolayers in the size range of 7–11 nm, which showed higher turn-over frequency values (TOF) and C7-asphaltene (C7-ASP) conversions than monometallic WS2 or Co9S8 catalysts in the VR HCK at 693 K and 10.0 MPa H2. Moreover, the extended X-ray fine absorption structure spectroscopy (EXAFS) coupled with the density functional theory (DFT) calculations successfully verified the formation of the Co-W-S phase.

Beneficial effect of V on stability of dispersed MoS2 catalysts in slurry phase hydrocracking of vacuum residue: XAFS studies

The structure and the catalytic activity of the dispersed VxMo(1−x)S2catalysts were investigated for hydrocracking (HCK) of vacuum residue (VR) with the same amount of catalyst loading of 0.113 mmol as a metal basis at 693 K and 9.5 MPa H2. The catalysts were prepared in situ in the reaction using vanadium acetylacetonate and molybdenum hexacarbonyl as V and Mo precursors, respectively. Structural properties of the dispersed catalysts were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy and transmission electron microscopy, which confirmed the formation of a well-dispersed V-MoS2phase in size range 6–8 nm. Furthermore, it was demonstrated that the V-MoS2catalysts feature higher stability in the catalyst recycle test for the VR HCK in terms of H2 consumption rate (TOF) and asphaltene conversion in comparison to monometallic sulfides of V2S3 or MoS2.

Gasoline and diesel-like fuel production via hydrocracking of hydrotreated tire pyrolytic oil over Ni-W/MCM-41 derived from blast furnace slag

This work reports the conversion of tire pyrolytic oil (TPO) to fuels via hydrotreatment followed by hydrocracking (HC) processes over Ni–W/MCM-41 and Ni–W/Al-MCM-41 catalysts. The catalysts were hydrothermally synthesized using the blast furnace slag (BFS) derived silica followed by precipitation of metals oxide. The catalysts physiochemical properties were investigated via several analysis tools. The TEM results revealed the ordered mesoporous MCM-41 formation and the metal oxide particles distribution on its surface. The XPS and TPR analyses confirmed the metals oxide existence on the MCM-41 support surface while incorporation into the support was observed for Ni–W/Al-MCM-41 catalyst. The Ni–W/Al-MCM-41 catalyst possessed the higher HC activity and 97.7% hydrodesulfurization. The high activity was explained via the surface area, pore size and catalyst acidity. Both catalysts have successfully produced gasoline and diesel-like fractions corresponding to the EN228 and EN590 specifications. The hydrocracked oil produced a 35 wt% of gasoline and 33% diesel upon fractionation.

ZEOLIT CRACKING CATALYST

Nowadays, refiners are facing a continuing need to add bottom processing by catalytic process (catalytic cracking and hydro cracking processes) capacity a result of gradually deteriorating crude oil quality and flat-to-declining for residualfuel oil.

Bahan Bakar Minyak Dari Berbagai Metode Konversi Sampah Plastik

The use of plastic and goods made of plastic have been rising in day to day. Increasing use of plastics is a consequence of the development of technology, industry and population. On one hand, the invention of plastic has a remarkable positive impact, because it has many advantages compared to other materials. But on the other hand, the plastic waste has negative impact that too worried, so its solutions need to be looked for. One of the alternative handling of plastic waste that currently extensively researched and developed is converting plastic waste into fuel. Converting plastic waste into fuel oil can be done with cracking process. There are three kinds of process that is hydro cracking, thermal cracking and catalytic cracking. Fuel oil produced from the cracking of plastic waste depending on the plastic type, cracking process used, catalyst type, pyrolisis temperature and condenser temperature.

Modeling and simulation of a bench-scale bubble column reactor for slurry phase hydrocracking of vacuum residue

A modeling and simulation were conducted to study the slurry phase hydrocracking of vacuum residue in a bench-scale slurry bubble column reactor (SBCR). The reactor model was based on axial dispersion, and the intrinsic kinetic information was reported in continuous stir tank reactor (CSTR) using the same feedstock in our previous study. The model was validated over a wide range of operating conditions using experimental data from the bench scale unit. The reactor model predicted product yields, sulfur and asphaltenes content with an average error of less than 10%. The bench-scale SBCR demonstrated better hydrocracking (HCK) and hydrotreating (HDT) performance compared to CSTR, mainly due to the mixing behavior in the SBCR. A stability index of asphaltene was proposed from the data reported in our previous study to evaluate the operating conditions. Based on the simulation results, the optimal operating conditions for recycle operating mode were suggested using the simultaneous optimization variables technique.

Effect of the chemical composition of six hydrotreated light cycle oils for benzene, toluene, ethylbenzene, and xylene production by a hydrocracking process

The effect of the chemical composition of the hydrotreated light cycle oil (HDT LCO) on the benzene, toluene, ethylbenzene, and xylene (BTEX) production by a hydrocracking (HCK) procedure, is presented. Six different types of HDT LCOs were obtained by submitting two types of LCOs to hydrotreating (HDT) with different catalysts and experimental conditions. The products were analyzed as mono-, di- and tri-aromatic compounds using the supercritical fluid chromatography (SFC) method (ASTM D5186). The HDT LCOs were subjected to HCK with a 50/50 in weight mixture of nickel-molybdenum on alumina (NiMo/Al2O3) and H-ZSM5 (NiMo/H-ZSM5, 50/50) at 375 °C, 7.5 MPa, 1.2 h−1, and 750 m3/m3 H2/Oil. The HCK products were analyzed by gas chromatography with a flame ionization detector (GC-FID) and divided into five groups: gas, light hydrocarbons (LHCs), BTEX, middle hydrocarbons (MHCs), and heavy hydrocarbons (HHCs).The results showed that the BTEX formation ranged from 27.0 to 29.8 wt.% and it did not show a significant dependence on the mono-aromatic (59.9 and 75.6 wt.%), total aromatic (61.1–84.2 wt.%) contents or MHCs conversion (58.3–64.3 wt.%) from the departing HDT LCO feedstock. This result implies that, contrary to previous expectations, the BTEX formation does not directly depend on the amounts of total or mono-aromatic compounds when departing from real feedstocks. A GC-PIONA (paraffin, isoparaffin, olefin, naphthene, aromatic) characterization method (ASTM D6623) for mechanism understanding purpose was also carried out.

Structure and activity of unsupported NiWS2 catalysts for slurry phase hydrocracking of vacuum residue: XAFS studies

The catalytic activities of the dispersed NixW(1−x)S2 catalysts were investigated for hydrocracking (HCK) of vacuum residue (VR) at 693 K, 9.5 MPa H2 with the same amount of catalyst loading of 0.113 mmol as a metal basis. The catalysts were prepared in situ in the reaction using nickel acetylacetonate and tungsten hexacarbonyl as Ni and W precursors, respectively. Structural properties of the dispersed catalysts were characterized by extended X-ray absorption fine structure and transmission electron microscopy, which confirmed the formation of a well-dispersed NixW(1−x)S2 phase in the size range 8–10 nm. Moreover, it was demonstrated that the bimetallic metal sulfides of NixW(1−x)S2 feature promotional activity in the VR HCK, showing higher turnover frequency values and less coke formation in VR HCK than monometal sulfides.

Clariant and Wuxi Xiyuan sign two more contracts in China

This work assesses, technically, economically and environmentally, the production of a liquid electrofuel, with the potential to replace conventional petrol. A conceptual design of a Power-to-Liquids process, which considers wind electricity and captured CO2, was taken as a starting point for developing a process model in the commercial software Aspen Plus. The flowsheet includes water electrolysis, and the reverse water-gas shift (rWGS), Fischer-Tropsch (FT) and hydrocracking (HC) processes. The environmental impact assessment (EIA) of the process was conducted by means of the SimaPro 8 software, following a cradle-to-gate scope and the ReCiPe 2016 LCA damage model. The economic analysis was carried out in Aspen Process Economic Analyzer, after including the quoted costs for the electrolyser and reactors. We found that under current market conditions, the production cost of the electrofuel is higher than that of petrol in the UK for 2018 (10.03 USD/GGE and 1.71 USD/gal, respectively). However, the produced fuel shows better environmental performance than conventional gasoline in all three categories at the endpoint level (Human health, Ecosystems and Resources), which should become a major driver for its widespread adoption.

Beneficial roles of carbon black additives in slurry phase hydrocracking of vacuum residue

Effects of carbon black (CB) additives with dispersed MoS2 catalysts (d-MoS2) on the slurry phase hydrocracking (HCK) of vacuum residue (VR) were studied in an autoclave batch reactor at 693 K and 9.5 MPa H2. For comparison, commercial NiMo catalysts supported on large and small pore volume Al2O3 (-LP, -SP) were also applied for the VR HCK. The structure of the catalysts was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS). The dispersed MoS2 (d-MoS2) was observed to form nanosized single slabs of 8.4 nm, while in the presence of CB the particle size of the d-MoS2-CB became even smaller (4.8 nm). A series of recycle runs of the VR HCK revealed high activity and stability of d-MoS2-CB followed by d-MoS2 > NiMo-LP > NiMo-SP. The kinetic analysis also demonstrated that the d-MoS2-CB shows a high asphaltene conversion with minimizing coke formation.

Highly active and stable MoWS2 catalysts in slurry phase hydrocracking of vacuum residue

Dispersed MoxW(1−x)S2 catalysts were obtained in situ in the hydrocracking (HCK) of vacuum residue (VR) at 693 K at 9.5 MPa H2 with the same metal loading of 0.113 mmol with varying Mo:W ratios. The intrinsic activities of the catalysts were compared based on the H2 consumption rate per the surface site number, i.e. TOFs. The Mo0.75W0.25S2 catalyst showed a superior activity with a high TOFs of 0.6012 s−1 over those of monometallic sulfides of MoS2 (0.4764 s−1) or WS2 (0.2550 s−1). Transmission electron microscopy (TEM) analysis identified that the morphology and average particle size of the MoWS2 catalyst maintains even after three times of recycles. Moreover, extended X-ray absorption fine structure (EXAFS) analysis confirmed homogeneous distribution of Mo and W species in the MoWS2 phase.

A mixed integer nonlinear programming approach for integrated bio-refinery and petroleum refinery topology optimization

Abstract The conversion of biomass into gasoline and diesel in bio-refinery process is an attractive process given its carbon neutral and sustainable nature. The economics of bio-refinery can be improved via integration with petroleum refinery, whereby bio-refinery intermediates can be processed into gasoline and diesel in the well-established petroleum refinery processing units, i. e., hydrocracking (HC) and fluidized catalytic cracking (FCC) units. However, the integration of the new bio-refinery into the existing petroleum refinery may not give the optimum solution given the capacities constraints of the existing petroleum refinery upgrading units such as FCC and HC units. Thus, this work proposed a superstructure comprising new bio-refinery and new petroleum refinery block diagrams. The superstructure was formulated into mixed integer nonlinear programming (MINLP) model. The model was coded into general algebraic modeling system (GAMS) platform and solved using global optimum solver, LINDOGLOBAL. The model application was demonstrated using representative case study. The model results showed that the optimum integrated bio-refinery and petroleum refinery topology favors the upgrading of bio-refinery intermediates using petroleum refinery HC unit under one-through operation mode with a marginal increase in the profit of about 0.39% compared to the second optimum case of upgrading bio-refinery intermediate using petroleum refinery FCC unit under gasoline operation mode. Thus, the decision in selecting the most suitable topology can be made based on the market demand for gasoline and diesel as the topology that uses FCC maximizes gasoline production and the topology that uses HC maximizes diesel production.

Power-to-fuel conversion based on reverse water-gas-shift, Fischer-Tropsch Synthesis and Hydrocracking: Mathematical modeling and simulation in Matlab/Simulink

Defossilization of the transport sector must contribute to the drastic reduction of CO2 emissions within the next three decades to limit global warming. The production of synthetic liquid fuels from CO2, water, and renewable electric energy can be one option. A Power-to-Fuel process is modeled based on Reverse Water-Gas-Shift Reaction, Fischer-Tropsch Synthesis (FTS) and Hydrocracking (HC). Different process configurations are investigated - optional intermediate product separation between FTS and HC, and recycle of unreacted streams (wax, tail gas). For practical application, we suggest direct coupling of FTS and HC, as intermediate product separation improves the liquid fuel yield just by a few percent. Compact processes are particularly important for flexible small-scale plants for decentralized application in the context of the energy transition. Wax recycling improves the liquid fuel yield slightly up to 6%. Gas recycling, however, with a ratio of only 0.4 considerably improves it by almost 80%.