Hydrocarbon Product Distribution Research Articles

CFD modeling of a mini-pilot scale CO2 hydrogenation to hydrocarbons reactor using both direct and indirect pathway-based kinetic model

Both indirect CO2 hydrogenation (reverse water gas shift (RWGS) followed by CO-based Fischer-Tropsch synthesis (FTS)) and direct CO2-based FTS were considered for CO2 hydrogenation, and a kinetic model for the chain-length distribution of hydrocarbon products was developed. For independent estimation, the kinetic parameters were estimated by fitting the experimental data using powder catalysts under various conditions, mainly including CO/CO2 ratios. The contribution of indirect CO2 hydrogenation (RWGS followed by CO-FTS) was more favorable than that of direct CO2-FTS, and CO2 conversion and product selectivity were significantly dependent on the temperature and hydrogen fraction. The effectiveness factor was estimated for the pellet-type catalysts, and values less than one validated the existence of mass-transfer resistance. Computational fluid dynamics (CFD) modeling was used to simulate the three-dimensional thermal behaviors of a mini-pilot-scale reactor with a substantially large diameter loaded with a pellet-type catalyst and inert materials. Both a low catalyst loading in the early stage of the reactor and the use of an additional inner cooling tube showed a stable temperature profile, with the peak temperature maintained below 350 °C (the critical temperature to prevent the thermal decomposition of chemicals) and fast heating of cold feed in the early stage. The CFD results with no inner tube showed thermal runaway in the second reactor, and the simulation with arbitrarily reduced heat of the reaction (70 % of the actual value) resulted in a peak temperature higher than 410 °C. Further quantitative analysis indicated that the no-inner-tube case's reduced heat transfer area per unit volume was responsible for its thermally unstable behavior.

PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite.

The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts - zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors. However, GC is not suitable for the detection of highly reactive intermediates such as ketene or formaldehyde and is not suitable for kinetic studies under well defined low pressure conditions. Photoelectron-photoion coincidence (PEPICO) spectroscopy has emerged as a powerful analytical tool for unraveling complex compositions of catalytic effluents, but its availability is limited to a handful of facilities worldwide. Herein, PEPICO analysis of catalytic reactor effluents has been implemented at the FinEstBeAMS beamline of MAX IV Laboratory. The conversion of dimethyl ether (DME) on a zeolite catalyst (ZSM-5-MFI27) is used as a prototypical model reaction producing a wide distribution of hydrocarbon products. Since in zeolites methanol is quickly equilibrated with DME, this reaction can be used to probe vast sub-networks of the full MTH process, while eliminating or at least slowing down methanol-induced secondary reactions and catalyst deactivation. Quantitative discrimination of xylene isomers in the effluent stream is achieved by deconvoluting the coincidence photoelectron spectra.

Upgrading CO2 to sustainable aromatics via perovskite-mediated tandem catalysis

The directional transformation of carbon dioxide (CO2) with renewable hydrogen into specific carbon-heavy products (C6+) of high value presents a sustainable route for net-zero chemical manufacture. However, it is still challenging to simultaneously achieve high activity and selectivity due to the unbalanced CO2 hydrogenation and C–C coupling rates on complementary active sites in a bifunctional catalyst, thus causing unexpected secondary reaction. Here we report LaFeO3 perovskite-mediated directional tandem conversion of CO2 towards heavy aromatics with high CO2 conversion (> 60%), exceptional aromatics selectivity among hydrocarbons (> 85%), and no obvious deactivation for 1000 hours. This is enabled by disentangling the CO2 hydrogenation domain from the C-C coupling domain in the tandem system for Iron-based catalyst. Unlike other active Fe oxides showing wide hydrocarbon product distribution due to carbide formation, LaFeO3 by design is endowed with superior resistance to carburization, therefore inhibiting uncontrolled C–C coupling on oxide and isolating aromatics formation in the zeolite. In-situ spectroscopic evidence and theoretical calculations reveal an oxygenate-rich surface chemistry of LaFeO3, that easily escape from the oxide surface for further precise C–C coupling inside zeolites, thus steering CO2-HCOOH/H2CO-Aromatics reaction pathway to enable a high yield of aromatics.

Synergistic effect of Zr and K promoters on iron-based catalysts in CO hydrogenation reaction

There is a growing demand for decreasing fossil fuel usage. That being said, we should move toward renewable and sustainable energy sources. Iron-based catalysts are usually employed in this route. In this work, an incipient impregnation process was used for preparing four γ-Al2O3 supported iron-based catalysts with different weight percents including 20Fe/5Cu/γ-Al2O3, 20Fe/5Cu/2K/γ-Al2O3, 20Fe/5Cu/3Zr/γ-Al2O3 and 20Fe/5Cu/1.5Zr/1K/γ-Al2O3 under the pressure of 20 atm, the temperature of 285 °C, H2 to CO ratio of one, and a gas hourly space velocity of 2 NL/ (h. gCat). BET, FE-SEM, XRD, H2-TPR, ICP, and TEM techniques were used to determine the characteristics of the catalysts, while gas chromatography results were used to determine CO conversion and product selectivity. Due to the synergistic effect of the two promoters, the doubly-promoted catalyst exhibited a C5+ selectivity of 64.2 %, surpassing both the Fe/Cu/γ-Al2O3 catalyst and the singly-promoted catalysts. This result highlights the enhanced performance of the doubly-promoted catalyst. Compared to the other catalysts prepared, the doubly-promoted catalyst demonstrated a higher carbon monoxide (CO) conversion rate of 67.7 % and yield of 43.5 %. Moreover, The results demonstrate the significant impact of Zr and K promoters of the synthesized Fe-based catalysts on hydrocarbon product distribution.

Experimental investigation on hydrocarbon generation of organic-rich shale with low maturity in sub- and supercritical water

Sub- and supercritical water, as solvents for organic matters, are promising for hydrocarbon generation of low maturity organic-rich shale. However, there is still no noteworthy study on the difference of dynamic hydrocarbon generation of low maturity organic-rich shale between sub- and supercritical water conditions. In this study, a non-isothermal heating reactor was used to simulate the hydrocarbon generation experiment of low maturity organic-rich shale at 360 °C, 21 MPa subcritical water and 400 °C, 25 MPa supercritical water within the range of 2–12 h. The differences of the hydrocarbon generation performance, product distribution, mineral composition and pore size distribution evolution between sub- and supercritical water condition were investigated. The results showed that the utilization degree of organic carbon and gas yield under supercritical water conditions were higher than that under subcritical water conditions at any given time within 2–12 h. The supercritical water condition had the advantage of an oil yield before 10 h, which was surpassed by subcritical water condition after 10 h. The relative content of saturated hydrocarbon and aromatic hydrocarbon were higher than resin and asphaltene under both sub- and supercritical water condition. The oil produced under subcritical water condition had more aromatic hydrocarbons. The selectivity of supercritical water for H2, CH4, C2H4 and C2H6 was higher than that of subcritical water, and the selectivity of subcritical water for CO2 was higher than that of supercritical water within the range of 0–12 h. The pyrite removing and pore expansion effects of supercritical water were greater than subcritical water. The mechanism of supercritical water to enhance the utilization degree of organic carbon mainly includes the enhancement of thermal efficiency, solubility, diffusion in terms of physical property effect, and the promotion of free radical reaction in terms of chemical property effect. We hope that the results will provide technical and theoretical support for in-situ hydrocarbon generation of low-mature organic-rich shale.

Methanol mediated direct CO2 hydrogenation to hydrocarbons: Experimental and kinetic modeling study

Carbon dioxide can be utilized as a feedstock to produce chemicals and renewable fuels sustainably. CO2 hydrogenation to hydrocarbons through a methanol mediated pathway requires a more detailed study, examining interactions between reaction processes leading to different product selectivities. In this particular work, we propose a kinetic model for the direct CO2 hydrogenation to different hydrocarbon products over an In2O3/HZSM-5 bifunctional catalytic bed. The model includes a CO2 hydrogenation to methanol model based on a Langmuir Hinshelwood Hougen Watson (LHHW) reaction mechanism over In2O3 catalyst combined with a lump-type methanol to hydrocarbon (MTH) model over the HZSM-5 zeolite. Interestingly, the combined model could largely predict the suppression of the reverse water gas shift (RWGS) reaction and an increase in the yield of hydrocarbons compared to the formation of methanol in case of the same reaction conditions carried out with only the methanol synthesis catalyst (In2O3). Further, by varying the mass ratio of the individual components of the bifunctional catalytic bed, it was demonstrated that a higher outlet concentration of methanol achieved with a higher mass ratio of the methanol synthesis catalyst caused less suppression of the RWGS reaction and shifted the hydrocarbon product distribution to a slightly larger share of higher hydrocarbons. These changes in product selectivity caused by variation of the catalyst mass ratio were both also successfully reproduced by the model. Therefore, a comparison between the experimental results and the model predictions shows that this model, including equilibrium effects for the reactions, can accurately predict the trends of the experimental findings for direct CO2 hydrogenation to hydrocarbons over the In2O3/HZSM-5 catalyst.

Kinetic Study of Product Distribution Using Various Data-Driven and Statistical Models for Fischer-Tropsch Synthesis.

Three modeling techniques, namely, a radial basis function neural network (RBFNN), a comprehensive kinetic with genetic algorithm (CKGA), and a response surface methodology (RSM), were used to study the kinetics of Fischer–Tropsch (FT) synthesis. Using a 29 × 37 (4 independent process parameters as inputs and corresponding 36 responses as outputs) matrix with total 1073 data sets for data training through RBFNN, the established model is capable of predicting hydrocarbon product distribution i.e., the paraffin formation rate (C2–C15) and the olefin to paraffin ratio (OPR) within acceptable uncertainties. With additional validation data sets (15 × 36 matrix with total 540 data sets), the uncertainties of using three different models were compared and the outcomes were: RBFNN (±5% uncertainties), RSM (±10% uncertainties), and CKGA (±30% uncertainties), respectively. A new effective strategy for kinetic study of the complex FT synthesis is proposed: RBFNN is used for data matrix generation with a limited number of experimental data sets (due to its fast converge and less computation time), CKGA is used for mechanism selections by the Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach using a genetic algorithm to find out potential reaction pathways, and RSM is used for statistical analysis of the investigated data matrix (generated from RBFNN through central composite design) upon responses and subsequent singular/multiple optimizations. The proposed strategy is a very useful and practical tool in process engineering design and practice for the product distribution during FT synthesis.

Pyrolysis of bio-derived dioxolane fuels: A ReaxFF molecular dynamics study

Alkyl-substituted 1,3-dioxolanes, including 4,5-dimethyl-2-pentan-3-yl-1,3-dioxolane (Fuel 1), 4,5-dimethyl-2-pentyl-1,3-dioxolane (Fuel 2), and 2-(heptan-3-yl)-4,5-dimethyl-1,3-dioxolane (Fuel 3), have been recently suggested as potential biodiesels. In this paper, we investigate the initial pyrolysis of the alkyl-substituted 1,3-dioxolanes at high temperatures using ReaxFF molecular dynamics (MD) simulations. We analyze the decomposition rate, reaction mechanism, and product distribution in the pyrolysis of the three alkyl 1,3-dioxlanes. The three fuels primarily decompose to 4,5-dimethyl-1,3-dioxolane radical and hydrocarbons derived from the alkyl side-chains. The further decomposition of 4,5-dimethyl-1,3-dioxolane radical primarily leads to 2-C4H8 and CO2 within a few decomposition steps. The hydrocarbon product distribution is significantly affected by the molecular structure of the alkyl side-chain, which would have a strong influence on the sooting tendency of these fuels. The ReaxFF simulations predict that the order of sooting tendency would be Fuel 3 > Fuel 1 > Fuel 2, which agrees with the measured sooting tendency trend. Based on the pyrolysis mechanism identified by ReaxFF, we propose a new alkyl dioxolane, 4-hexyl-5-methyl-1,3-dioxolane (Fuel 4), which might produce even less soot, by modifying the molecular structure of Fuel 2. Our ReaxFF simulation shows that Fuel 4 produce much less C4H8, an effective non-aromatic soot precursor, than Fuel 2. Moreover, more carbon atoms are bonded to each oxygen atom in Fuel 4 than Fuel 2, which would help reduce soot yield by removing more carbon atoms from the soot-producing pool of species. The major decomposition pathways identified in this work can be used to develop chemical kinetic models for 1,3-dioxolane based compounds, as biodiesel components, applicable to combustion engine simulations. We also demonstrate that the chemical kinetic insight offered by ReaxFF simulations can be used to design new fuel molecules with more desired properties.

Design of Cobalt Fischer-Tropsch Catalysts for the Combined Production of Liquid Fuels and Olefin Chemicals from Hydrogen-Rich Syngas.

Adjusting hydrocarbon product distributions in the Fischer–Tropsch (FT) synthesis is of notable significance in the context of so-called X-to-liquids (XTL) technologies. While cobalt catalysts are selective to long-chain paraffin precursors for synthetic jet- and diesel-fuels, lighter (C10–) alkane condensates are less valuable for fuel production. Alternatively, iron carbide-based catalysts are suitable for the coproduction of paraffinic waxes alongside liquid (and gaseous) olefin chemicals; however, their activity for the water–gas-shift reaction (WGSR) is notoriously detrimental when hydrogen-rich syngas feeds, for example, derived from (unconventional) natural gas, are to be converted. Herein the roles of pore architecture and oxide promoters of Lewis basic character on CoRu/Al2O3 FT catalysts are systematically addressed, targeting the development of catalysts with unusually high selectivity to liquid olefins. Both alkali and lanthanide oxides lead to a decrease in turnover frequency. The latter, particularly PrOx, prove effective to boost the selectivity to liquid (C5–10) olefins without undesired WGSR activity. In situ CO-FTIR spectroscopy suggests a dual promotion via both electronic modification of surface Co sites and the inhibition of Lewis acidity on the support, which has direct implications for double-bond isomerization reactivity and thus the regioisomery of liquid olefin products. Density functional theory calculations ascribe oxide promotion to an enhanced competitive adsorption of molecular CO versus hydrogen and olefins on oxide-decorated cobalt surfaces, dampening (secondary) olefin hydrogenation, and suggest an exacerbated metal surface carbophilicity to underlie the undesired induction of WGSR activity by strongly electron-donating alkali oxide promoters. Enhanced pore molecular transport within a multimodal meso-macroporous architecture in combination with PrOx as promoter, at an optimal surface loading of 1 Prat nm–2, results in an unconventional product distribution, reconciling benefits intrinsic to Co- and Fe-based FT catalysts, respectively. A chain-growth probability of 0.75, and thus >70 C% selectivity to C5+ products, is achieved alongside lighter hydrocarbon (C5–10) condensates that are significantly enriched in added-value chemicals (67 C%), predominantly α-olefins but also linear alcohols, remarkably with essentially no CO2 side-production (<1%). Such unusual product distributions, integrating precursors for synthetic fuels and liquid platform chemicals, might be desired to diversify the scope and improve the economics of small-scale gas- and biomass-to-liquid processes.

Safety Case Development For Risk Management Of Offshore Pipeline

Offshore pipeline is an indispensable component that plays a huge role in the distribution of hydrocarbon products. Thus, it is necessary to prevent any kind of incidents that may bring harm to the offshore pipeline system. Therefore, this paper is intended to develop the structure of Safety Case Document which provides preventions and mitigations actions and formulate risk management approach for offshore pipeline. Offshore pipeline that was specifically being used as a data in this project is located at Northeast of Java Sea and possesses 1 km of length. This pipeline has sustain from pipeline leakage, therefore this paper will identify the risk assessment for pipeline damage.. The methods that was being involved in this project are as follows; HAZID to identify the cause of the failure of the pipeline and Fuzzy FMEA to determine the Risk Priority Number in order to find out the priority of each failure cause. HAZID also useful to provide the necessary prevention and mitigation actions in accordance to each cause and subsequently being structured as a Safety Case Document.

Effect of Ba and CN Additives on the Catalytic Performance of Co/Al2O3 in Fischer−Tropsch Synthesis

AbstractA simple and effective method to modify Co/Al2O3 catalyst to improve the catalytic performance in Fischer‐Tropsch synthesis reaction is described. It is found that the electron density on the cobalt surface increases via electron donation from the dopant Ba and CN species, leading to an enhanced C5+ selectivity and C3 o/p ratio. However, the presence of Ba increases the cobalt crystalline size while the introduction of CN species leads to the formation of smaller cobalt nanoparticles and greatly increases their dispersion, thus resulting in a different distribution of heavy hydrocarbon products. Our work offers a new avenue to obtain catalyst with high activity and selectivity.

Brown grease pyrolysis under pressure: Extending the range of reaction conditions and hydrocarbon product distributions

Pyrolysis of brown grease to hydrocarbon products was performed in a pressure reactor. Compared to our previous work at atmospheric pressure, higher reaction temperatures could be achieved. These resulted in shorter reaction times, reduced formation of undesirable ketone byproducts, and a higher percentage of the most valuable light hydrocarbon products. Higher temperatures did, however, increase the percentage of gas products at the expense of liquid products. The major liquid products are alkanes ranging from heptane to heptadecane, with smaller amounts of cycloalkanes, and in some cases, aromatic compounds.

Effect of EDTA-2Na modification on Fe-Co/Al2O3 for hydrogenation of carbon dioxide to lower olefins and gasoline

Capturing and utilization of carbon dioxide (CO2) not only leads to effective use of carbon resources, but also alleviates environmental pollution caused by increasing concentration of CO2, thus making it a hot research topic in recent years. In this study, a series of highly dispersed iron-cobalt (Fe-Co) catalysts was prepared by ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) modification, which could efficiently convert CO2 into high value-added chemicals (C2-C4= and C5-C11). X-ray diffraction (XRD) analysis showed that the addition of a small amount of Co and EDTA-2Na contributed to enhance the sintering resistance of Fe species. During the calcination process, EDTA4− can be decomposed into small organic molecules with reducibility, thus promoting the reduction of iron species. The CO temperature-programmed desorption (CO-TPD) results showed that cobalt enhanced the adsorption and activation of intermediate CO on NaxFe-Co catalyst, thereby promoting the catalytic conversion of CO2. The complexation of EDTA promotes the synergistic effect of Fe-Co bimetals, enhances the chemical adsorption of CO2. Sodium in EDTA-2Na promotes the surface basicity of the catalysts, which is favored for improving the product distribution of hydrocarbons. At lower H2/CO2 (1/1) ratio, the EDTA-2Na modified Fe-Co/Al2O3 catalyst exhibited high conversion of CO2 (32.8 %) and excellent selectivity toward high value-added chemicals. The selectivity of by-product CO was only 8.1 %; and C2-C4= (32.5 %) and C5-C11 (46.3 %) accounted for ∼79 % selectivity among the hydrocarbons generated.

Plasma-assisted catalytic dry reforming of methane (DRM) over metal-organic frameworks (MOFs)-based catalysts

Plasma-assisted dry reforming of methane (DRM) was performed in a dielectric barrier discharge (DBD) reactor. The effect of different packing materials including ZrO2, UiO-67 MOF and PtNP@UiO-67 on plasma discharge was investigated, showing that ZrO2 suppressed the plasma generation while UiO-67 improves it due to its porous nature which favours the formation of filamentary microdischarges and surface discharges. The improved plasma discharge increased the conversion of CH4 and CO2 by about 18% and 10%, respectively, compared to the plasma-alone mode. In addition, the distribution of hydrocarbon products changed from dominant C2H6 in the plasma-alone mode to C2H2 and C2H4 in the UiO-67 promoted plasma-assisted DRM. The UiO-67 MOF was stable in plasma, showing no significant changes in its properties under different treatment times, discharge powers and gases. Pt nanoparticles (NPs) on UiO-67 improved plasma-assisted DRM, especially the selectivity due to the presence of surface reactions. Due to the dehydrogenation of hydrocarbons over Pt NPs, the selectivity to hydrocarbons decreased by 30%, compared to the UiO-67 packing. In situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS) was carried out to probe the surface reactions on PtNP@UiO-67 catalyst, showing the decomposition of surface formats to CO and C2H4 dehydrogenation over the metallic Pt. The PtNP@UiO-67 catalyst showed good reusability in the plasma-assisted DRM, and H2 production was improved by high CH4/CO2 molar ratio and low feed flow rate.

Catalytic conversion of rubber wastes to produce aromatic hydrocarbons over USY zeolites: Effect of SiO2/Al2O3 mole ratio

Catalytic conversion of rubber wastes to produce an alternative fuel resource is a promising approach to dispose of solid wastes and address environmental issues. In this study, catalytic fast pyrolysis (CFP) of rubber wastes over acidic zeolites was conducted, and the effect of SiO2/Al2O3 mole ratio of USY zeolites on the formation of aromatic hydrocarbons was explored. Experimental results indicated that alkenes and aromatic hydrocarbons were the main pyrolytic products obtained from fast pyrolysis of rubber wastes, and the pyrolysis temperature played a vital role in the formation of aromatics with the highest concentration achieved at 750 °C. Moreover, catalyst types also affected the catalytic degradation of rubber wastes since limonene was completely decomposed in the presence of zeolites. Compared to SAPO-34, zeolites with higher external surface area, stronger Brønsted acid sites, and larger pore size, including USY, HY, and Hβ, were more effective in the production of aromatic hydrocarbons with the highest content obtained from USY catalyzed run. Given the observed effect of SiO2/Al2O3 mole ratio of USY zeolites on the formation of aromatic hydrocarbons during the CFP of rubber wastes, USY with low SiO2/Al2O3 ratio of 5.3 was more beneficial to the generation of aromatic hydrocarbons, while that with higher SiO2/Al2O3 mole ratio (11.5) facilitated the formation of alkenes. Simultaneously, the product distribution of aromatic hydrocarbons obtained from CFP of rubber wastes over USY zeolites was dominated by xylenes, alkylbenzenes, and toluene, and USY with SiO2/Al2O3 mole ratio of 5.3 was more active in the production of toluene and xylenes.

Methanol-to-Hydrocarbons Product Distribution over SAPO-34 and ZSM-5 Catalysts: The applicability of Thermodynamic Equilibrium and Anderson-Schulz-Flory Distribution

The product distribution of methanol to hydrocarbons conversion over SAPO-34 and ZSM-5 catalysts was studied using thermodynamic equilibrium and Anderson-Schulz-Flory (ASF) distributions. The equilibrium compositions were calculated using constrained Gibbs free energy minimization. The effect of catalyst type was considered by setting upper limits to product carbon number due to shape selectivity according to zeotype catalyst channel size; that is, n£5 for SAPO-34 but n£6 for aliphatic and n£10 for aromatic compounds over H-ZSM-5 catalyst. The equilibrium selectivity of kinds of paraffin is negligible over SAPO-34 system while that of olefins is very small over H-ZSM-5, both in agreement with experimental results for methanol to olefins and to gasoline, respectively. The methanol to olefins hydrocarbon product distributions over SAPO-34 and H-ZSM-5 showed fair agreements with thermodynamic equilibrium and ASF distributions, respectively. It was found that propylene is the only product the selectivity of which can be maximized among hydrocarbon products over both SAPO-34 and ZSM-5 catalysts, and therefore, it can be an easier target molecule in methanol to hydrocarbon conversions.

Controllable thermal conversion of thiomolybdate to active few-layer MoS2 on alumina for efficient hydrodesulfurization

Sulfur removal is the most challenging task in petroleum refineries for upgrading clean fuel from crude oil. In this regard, an efficient Ni–MoS2 catalyst was prepared using ammonium tetrathiomolybdate (ATM), (NH4)2MoS4 as a precursor for hydrodesulfurization (HDS) reaction. ATM was derived by sulfiding an aqueous ammoniacal ammonium heptamolybdate and impregnated on alumina support with and without nickel promoter to form a series of MoS2/Al2O3, and Ni–MoS2/Al2O3 catalysts with controlled calcination temperature. The prepared ATM and catalysts were characterized by X-ray diffraction (XRD), Infrared spectroscopy and nitrogen adsorption–desorption. The phase transformation of ATM to MoS2 was observed by TGA, and number of MoS2 layer formation was calculated from the frequency difference between the redshift and blueshift by Raman spectrum. The catalytic properties of MoS2/Al2O3, and Ni–MoS2/Al2O3 were investigated using thiophene as the model compound for HDS reaction. The HDS rate, C4 hydrocarbon product distribution and selectivity were quantified by microreactor with refinery gas analyzer system. The prepared MoS2 catalysts (MoS and NiMoS) at 350 °C showed a better conversion rate than another catalyst due to the synergy between the promoter and few-layered MoS2 on support. Thus, ATM is a suitable candidate for the formulation of Ni–MoS2 catalyst at 350 °C for improving thiophene HDS activity.

Selective preparation of monocyclic aromatic hydrocarbons from ex-situ catalytic fast pyrolysis of pine over Ti(SO4)2-Mo2N/HZSM-5 catalyst

To selectively produce monocyclic aromatic hydrocarbons (MAHs) with low amount of polycyclic aromatic hydrocarbons (PAHs), modified HZSM-5 catalysts (Mo2N/HZSM-5, Ti(SO4)2/HZSM-5 and Ti(SO4)2-Mo2N/HZSM-5) were prepared and employed for ex-situ catalytic fast pyrolysis (CFP) of pine wood. Both analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale pyrolysis experiments were conducted to investigate the effects of catalyst, pyrolysis temperature and catalyst-to-pine ratio on the distribution of aromatic hydrocarbon products. Py-GC/MS results showed that the maximal MAHs yields from the HZSM-5, Mo2N/HZSM-5, Ti(SO4)2/HZSM-5 and Ti(SO4)2-Mo2N/HZSM-5 catalysts were 7.57 wt%, 8.11 wt%, 8.71 wt% and 12.53 wt% at 650 °C and catalyst-to-pine ratio of 7. Corresponding PAHs yields from the four catalysts were 2.55 wt%, 0.97 wt%, 1.47 wt% and 1.10 wt%, which clearly indicated that the Ti(SO4)2-Mo2N/HZSM-5 significantly increased MAHs formation and decreased PAHs formation as compared with HZSM-5. Furthermore, lab-scale experiments were conducted to quantitatively determine the pyrolytic product distribution. Results showed that Ti(SO4)2-Mo2N/HZSM-5 catalyst increased the yield of liquid and gas products, and decreased solid products as compared with HZSM-5. Under optimal conditions of 650 °C and catalyst-to-pine ratio of 4/3, the actual yields of MAHs and PAHs from Ti(SO4)2-Mo2N/HZSM-5 catalyst were 9.71 wt% and 1.45 wt%, respectively. In addition, stability tests confirmed that the Ti(SO4)2-Mo2N/HZSM-5 catalyst possessed better effects on MAHs production as well as anti-deactivation than the HZSM-5.

Two-step catalytic hydrogenation of methanol to hydrocarbons conversion

Abstract The continuous two-step catalytic hydrogenation of methanol to hydrocarbons (MTH) was investigated for improving the distribution of liquid hydrocarbon products using HZSM-5 zeolite and consecutively with two supported Co catalysts, Co/Al2O3 and Co/SBA-15. The sequential catalytic system was employed to enhance the selectivity of long chain hydrocarbons. The catalysts were characterized by BET, XRD, XRF, NH3-TPD, and SEM techniques. The catalytic performance of prepared catalysts was performed at 300 oC in a fixed-bed reactor with the constant flow rate of methanol under 1 atm of N2. The liquid hydrocarbons were analyzed by GC-MS. The aromatic and light hydrocarbon products were produced by the HZSM-5 and Co-based catalysts. According to the analysis result, the aromatic hydrocarbon products of the catalysts modified by two-step of catalytic reaction have been significantly increased. The results indicated that the series of HZSM-5 and two supported Co catalysts system led to produce high yield of aromatic hydrocarbon products in the catalytic performance of methanol to hydrocarbon process comparing with only the single HZSM-5 catalyst.

Improvement of HZSM-5 catalytic performance by rice husk ash addition for methanol to hydrocarbons process

Abstract The catalytic conversion of methanol to hydrocarbons (MTH) of gasoline has been studied over the modification of HZSM-5 zeolite catalysts, which were prepared by different ratios of rice husk ash (RHA) addition. The catalysts were characterized by BET, XRD, XRF, NH3-TPD, FT-IR and SEM techniques. The dehydration of methanol over prepared catalysts was carried out in a fixed-bed reactor at 300 oC with a constant flow rate of methanol under 1 atm of N2. The liquid hydrocarbons product was analyzed by GC-MS. The analysis showed that the major product provided by RHA-HZSM-5 catalysts was aromatic hydrocarbon-rich. According to the experimental results, the methanol conversion to hydrocarbons has been found to be a function of RHA ratio. The aromatic product selectivity was increased but that of the acidity of catalyst was decreased with the increase of RHA ratio. The study indicated that the hydrocarbon product distribution of the catalysts treated by RHA significantly depended on the acidity of catalyst.