Selectivity Of Light Hydrocarbons Research Articles

Synthesis of Liquid Hydrocarbon via Direct Hydrogenation of CO2 over FeCu-Based Bifunctional Catalyst Derived from Layered Double Hydroxides.

Here, we report a Na-promoted FeCu-based catalyst with excellent liquid hydrocarbon selectivity and catalytic activity. The physiochemical properties of the catalysts were comprehensively characterized by various characterization techniques. The characterization results indicate that the catalytic performance of the catalysts was closely related to the nature of the metal promoters. The Na-AlFeCu possessed the highest CO2 conversion due to enhanced CO2 adsorption of the catalysts by the introduction of Al species. The introduction of excess Mg promoter led to a strong methanation activity of the catalyst. Mn and Ga promoters exhibited high selectivity for light hydrocarbons due to their inhibition of iron carbides generation, resulting in a lack of chain growth capacity. The Na-ZnFeCu catalyst exhibited the optimal C5+ yield, owing to the fact that the Zn promoter improved the catalytic activity and liquid hydrocarbon selectivity by modulating the surface CO2 adsorption and carbide content. Carbon dioxide (CO2) hydrogenation to liquid fuel is considered a method for the utilization and conversion of CO2, whereas satisfactory activity and selectivity remains a challenge. This method provides a new idea for the catalytic hydrogenation of CO2 and from there the preparation of high-value-added products.

A Core-Shell Structured Na/Fe@Co Bimetallic Catalyst for Light-Hydrocarbon Synthesis from CO2 Hydrogenation

The direct CO2 Fischer–Tropsch synthesis (CO2-FTS) process has been proven as one of the indispensable and effective routes in CO2 utilization and transformation. Herein, we present a core-shell structured Na/Fe@Co bimetallic catalyst to boost CO2 conversion and light hydrocarbon (C2 to C4) selectivity, as well as inhibit the selectivity of CO. Compared to the Na/Fe catalyst, our Na/Fe@CoCo-3 catalyst enabled 50.3% CO2 conversion, 40.1% selectivity of light hydrocarbons (C2-C4) in all hydrocarbon products and a high olefin-to-paraffin ratio (O/P) of 7.5 at 330 °C and 3.0 MPa. Through the characterization analyses, the introduction of CoCo Prussian Blue Analog (CoCo PBA) not only increased the reducibility of iron oxide (Fe2O3 to Fe3O4), accelerated the formation of iron carbide (FexCy), but also adjusted the surface basic properties of catalysts. Moreover, the trace Co atoms acted as a second active center in the CO2-FTS process for heightening light hydrocarbon synthesis from CO hydrogenation. This work provides a novel core-shell structured bimetallistic catalyst system for light hydrocarbons, especially light olefin production from CO2 hydrogenation.

A stable microporous framework with multiple accessible adsorption sites for high capacity adsorption and efficient separation of light hydrocarbons

Metal-organic frameworks (MOFs), a type of designable porous materials, are effectively employed to realize light hydrocarbons storage and separation in favor of energy conservation and environmental protection, superior to traditional separation technology. Significantly, a novel MOF, Ni2(L)2(HCOO)2·4H2O (1) has been constructed from a bifunctional group ligand of 3-hydroxy-4-(4H-1,2,4-triazol-4-yl) benzoic acid ligand (HL). MOF 1 possesses stable porous structure with narrow channels functionalized with multiple accessible adsorption sites of hydroxy group, carboxyl oxygen atoms from the L− and HCOO−, exhibiting a well trade-off between good capacity and selectivity for light hydrocarbons. The single-component sorption isotherm results of Ni2+ based MOF not only shows good gas sorption capacity for light hydrocarbons of C2H2, C2H6, C2H4, C3H8, and greenhouse gas CO2, especially remarkable uptake for C2H2 (122.0 cm3 g−1 at ambient condition), but also favorable selectivity for binary mixtures of C2H2/CH4, C2H6/CH4, C3H8/CH4, C2H4/CH4, C2H2/C2H4 as well as C3H8/C2H6/CH4 ternary mixture, as confirmed by ideal adsorbed solution theory (IAST) calculations, and dynamic breakthrough experiment. Grand canonical Monte Carlo (GCMC) simulation reveals the multiple synergism of accessible adsorption sites including functional OH groups, carboxylate groups, HCOO− and π···π stacking interaction between guest molecules and host-pore are crucial to contribute selective gas adsorption of light hydrocarbons.

Influence of the Borate on the Performance of ASA-Al2O3 supported Ni-Mo Hydrocracking Catalyst

The borate-doped and non-borated Ni-Mo/ASA-Al2O3 catalysts have been prepared and characterized by the BET, XRD, TGA, and NH3-TPD analysis. The catalyst’s performance was assessed in n-hexadecane hydrocracking using a downflow fixed bed micro-reactor. The stability of the catalysts in the presence of water and coke deposition was examined for the HCK of non-conventional feeds. The obtained results revealed that borate increased the feed percentage conversion from 91.43 to 99.21% compared to the not borated catalyst. This improvement is mostly due to the promotion of the acidic functions by BO3 addition. Results showed that the addition of borate increased the selectivity of light hydrocarbons and light gaseous products slightly (from 4.64 to 8.76%).

Substitution of Co with Ni in Co/Al2O3 Catalysts for Fischer–Tropsch Synthesis

The effect of cobalt substitution with nickel was investigated for the Fischer–Tropsch synthesis reaction. Catalysts having different Ni/Co ratios were prepared by aqueous incipient wetness co-impregnation, characterized, and tested using a continuously stirred tank reactor (CSTR) for more than 200 h. The addition of nickel did not significantly modify the morphological properties measured. XRD, STEM, and TPR-XANES results showed intimate contact between nickel and cobalt, strongly suggesting the formation of a Co-Ni solid oxide solution in each case. Moreover, TPR-XANES indicated that nickel addition improves the cobalt reducibility. This may be due to H2 dissociation and spillover, but is more likely the results of a chemical effect of intimate contact between Co and Ni resulting in Co-Ni alloying after activation. FTS testing revealed a lower initial activity when nickel was added. However, CO conversion continuously increased with time on-stream until a steady-state value (34%–37% depending on Ni/Co ratio) was achieved, which was very close to the value observed for undoped Co/Al2O3. This trend suggests nickel can stabilize cobalt nanoparticles even at a lower weight percentage of Co. Currently, the cobalt price is 2.13 times the price of nickel. Thus, comparing the activity/price, the catalyst with a Ni/Co ratio of 25/75 has better performance than the unpromoted catalyst. Finally, nickel-promoted catalysts exhibited slightly higher initial selectivity for light hydrocarbons, but this difference typically diminished with time on-stream; once leveling off in conversion was achieved, the C5+ selectivities were similar (≈ 80%) for Ni/Co ratios up to 10/90, and only slightly lower (≈ 77%) at Ni/Co of 25/75.

Activity and Structural Changes of Fe‐based Catalysts during CO2 Hydrogenation towards CH4 – A Mini Review

AbstractHeterogeneous iron catalysts are active in the hydrogenation of carbon oxides and are widely investigated for the production of long‐chained hydrocarbons according to the Fischer‐Tropsch synthesis. Moreover, high selectivity of light hydrocarbons, such as CH4, also occurs strongly depending on reaction conditions and catalyst formulations. As a consequence, Fe catalysts reveal promising methanation activity as referred to the traditional Ni catalysts. Additionally, Fe catalysts also benefit from their low price and toxicological harmlessness. However, the dynamic behavior of iron upon CO2 hydrogenation is not yet unraveled unambiguously including phase transformations, structural changes and participation of carbon species formed. The present review highlights these complex processes of Fe catalysts with special focus on the methanation of CO2. Additionally, different analytical tools useful for ex situ and in situ studies are critically evaluated.

Determination of selectivity equations heavy and light product of petroleum on iron based catalysts in Fischer-Tropsch synthesis

The optimal control of selectivity is an important method to trigger catalyst activity in the Fischer-Tropsch synthesis to produce favorable products. The determination of a model that will show the extent of product dependence on various parameters is of great importance in the Fischer-Tropsch synthesis. Efforts to increase a product in industry can be economical. In this research, a comprehensive method was evaluated to create a selectivity model of catalyst Fe/Cu/K/SiO2 of hydrocarbon products under conditions of temperature, pressure, and space velocity in a fixed-bed reactor. The response surface methodology was used in order to optimize process conditions and the relation of continuous functions between variables, so that the obtained model showed the selectivity of methane, light olefin hydrocarbons, heavy hydrocarbons products by factors such as temperature, pressure, and space velocity. A comparison of the models showed space velocity, among all the other factors, had a considerable effect on the increase selectivity of light hydrocarbons. On the other hand, the selectivity of methane indicates that temperature decrease parameter has the minimum effect on production. Whereas, the temperature rise cause reduces heavy hydrocarbons. The goal is to maximizing light hydrocarbon and minimizing methane and heavy hydrocarbon products.Highlights• Comprehensive equations to achieve selectivity model of hydrocarbon products.• The response surface methodology was used in order to optimize process conditions.• The optimum products condition was obtained by using the obtained equations.

Cation influence in adsorptive propane/propylene separation in ZIF-8 (SOD) topology

Separation of propylene/propane is one of the most challenging and energy consuming processes in the chemical industry. Propylene demand is increasing and a 99.5% purity is required for industrial purposes. Adsorption based solutions are the most promising alternatives to improve the economical/energetic efficiency of the process. Zeolitic Imidazolate Frameworks (ZIFs) combine the desired characteristics from both MOFs and zeolites: tunability and flexibility from metal organic frameworks, and exceptional thermal and chemical stability from zeolites. In order to enlighten the role of the cation in the sodalite ZIF-8 framework for propane/propylene separation, dynamic breakthrough measurements have been performed over ZIF-8(Zn), ZIF-67 (i.e. ZIF-8(Co)) and MUV-3 (i.e. ZIF-8(Fe)), all isostructural materials based on the same linker (2-methylimidazole). Cation substitution has a remarkable influence in the framework flexibility, and, consequently, in SOD-ZIF selectivity for light hydrocarbons. The differences between the crystallographic pore sizes of the material and the molecular dimensions of propane and propylene are so small, that the slightest change in the framework causes notable advantages/disadvantages in the final application. While cobalt is known to promote a more rigid framework resulting in an adsorption selectivity towards propane, iron presents the inverse effect yielding selectivity to propylene. Zinc has an intermediate effect. A threshold pressure in the isotherm is observed for propylene uptake by ZIF-67 at 273 and 298 K, and only at the lower temperature for ZIF-8. Inlet mixture composition does not highly influence the adsorptive selectivity, although it clearly affects the pure hydrocarbon recovery. Over ZIF-67 breakthrough experiments at 298 K yield a temporary pure propylene flow representing 10–15% of the amount fed. ZIF-67 is a promising candidate for propylene/propane adsorptive separation.

Fast Pyrolysis of Sunflower Oil in the Presence of Microporous and Mesoporous Materials for Production of Bio-Oil

The present work describes the study of micro (H-ZSM-5) and mesoporous (AL-MCM-41) structures, aiming at their application in the production of renewable fuels through the thermos-catalytic pyrolysis process both were synthesized hydrothermally and characterized by X-ray diffraction, thermal analysis, infrared spectroscopy, nitrogen adsorption, and surface acidity. The catalytic effect of the materials mentioned, as well as their mechanical mixtures in the proportions of H-ZSM-5 (75% wt) and AL-MCM-41 (25% wt); H-ZSM-5 (50% wt) and AL-MCM-41 (50% wt); H-ZSM-5 (25% wt) and AL-MCM-41 (75% wt) were used in the thermal and thermo-catalytic pyrolysis of sunflower oil. The products obtained in the presence of H-ZSM-5 (25% wt) and AL-MCM-41(75% wt) showed selectivity for the conversion of hydrocarbons between C11 and C16, which is near that of the petroleum-derived kerosene and diesel (>C16). On the other hand, the H-ZSM-5 (75% wt) and AL-MCM-41 (25% wt) material, in which the majoritarian catalyst is the microporous, with active sites and a higher surface acidity, indicates selectivity for light hydrocarbons (C5-C10), in the range of gasoline obtained by the conversion of mineral oil. The presence of catalysts (AL-MCM-41and H-ZSM-5) favors the deoxygenation of the pyrolysis products of sunflower oil by decarbonylation reaction.

Solvent-induced framework-interpenetration isomers of Cu MOFs for efficient light hydrocarbon separation

For a pair of Cu-paddlewheel framework-interpenetrating isomers, the interpenetrating framework exhibits a high adsorption and separation selectivity for light hydrocarbons.

The catalytic performance of different promoted iron catalysts on combined supports Al2O3 for carbon dioxide hydrogenation

Global warming, fossil fuel depletion and fuel price increases have motivated scientists to search for methods for the storage and reduction of the amount of greenhouse gases, especially CO2. The hydrogenation process has been introduced as an emerging method of CO2 capture and convertion into value-added products. In this study, new types of catalysts are introduced for CO2 hydrogenation and are compared based on catalytic activity and product selectivity. The physical properties of the samples are specified using BET. Iron catalysts supported on γ-Al2O3 with different metal promoters (X = Ni, K, Mn, Cu) are prepared through the impregnation method. Moreover, Fe–Ni catalysts supported on HZSM5-Al2O3 and Ce–Al2O3 are synthesized. Samples are reduced by pure H2 and involved in hydrogenation reaction in a fixed bed reactor (H2/CO2 = 3, total pressure = 10 MPa, temperature = 523 K, GHSV = 2000, 1250 nml/min). All catalysts provide high conversion in hydrogenation reactions and the results illustrate that the selectivity of light hydrocarbons is higher than that of methane and CO. It is found that Ni has a promoting effect on the conversion fluctuations throughout the reaction with 66.13% conversion. Using combined supported catalysts leads to enhancing catalytic performance. When Fe–Ni/γ–Al2O3—HZSM5 is utilized, CO2 conversion is 81.66% and the stability of the Fe–Ni catalyst supported on Al2O3 and Ce–Al2O3 furthey improves.

Tuning the selectivity of light hydrocarbons in natural gas in a family of isoreticular MOFs

The kinetic adsorption selectivity of methane versus other light hydrocarbons, present in natural gas, is tuned in a rationally synthesized family of isoreticular MOFs.

A preliminary evaluation of ZSM-5/SBA-15 composite supported Co catalysts for Fischer–Tropsch synthesis

A series of ZSM-5/SBA-15 composite supported Co catalysts were prepared and evaluated for the Fischer–Tropsch synthesis (FTS) aimed to maximise the selectivity of C5–C22 hydrocarbons in the product. The composite support was prepared by physically mixing ZSM-5 and SBA-15 of varying proportions and the finished catalysts had a constant Co loading of 15wt.%. The catalysts were tested for their performance in a high pressure fixed-bed reactor operating at T=240°C, P=2.0MPa, H2/CO=2 and GHSV=1000h−1. The composite supported catalysts were shown to have much improved catalytic performance over the respective single material supported catalysts. The catalyst with 20wt.% ZSM-5 in the composite support gave the maximum CO conversion (90.6%), maximum selectivity of C5–C22 hydrocarbons (70.0%) and minimum selectivity of light hydrocarbons (13.3% for CH4 and 7.0% for C2–C4 alkanes). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy with an energy dispersive X-ray spectrometer, temperature programmed desorption and temperature programmed reduction. It was revealed that the superior catalytic performance can be attributed to the large pore size and high dispersion of Co3O4, which afforded an optimum reducibility and acid site density.

A stable zinc-4-carboxypyrazole framework with high uptake and selectivity of light hydrocarbons.

A special organic ligand, 4-carboxypyrazole (4-cpz), is chosen to synthesize a highly stable metal-organic framework (MOF) for selective sorption of light hydrocarbons. The new MOF, (H(3)O)[Zn(3)(OH)(4-cpz)3]·2(DEF)·H(2)O (FIR-51, DEF = N,N-diethylformamide), was synthesized solvothermally and shows unusual chemical stability. This compound exhibits high storage capacity for light hydrocarbons and high selectivity for C3 and C2 over methane at 273 and 294 K.

A spin-canted Ni(II)4-based metal-organic framework with gas sorption properties and high adsorptive selectivity for light hydrocarbons.

The reaction of nickel(II) nitrate with isonicotinic acid and 2,6-dimethyl-pyridine-3,5-dicarboxylic acid affords a novel, tetranuclear nickel(II)-based metal-organic framework that exhibits spin-canted antiferromagnetism with a canted angle of 1.65° and high adsorptive selectivity for light hydrocarbons.

Fischer-Tropsch Synthesis over Co/SiO<sub>2</sub> Catalysts Modified with Ethylenediamine

The influence of ethylenediamine (en)/Co molar ratio on the preparation of Co/SiO2 catalysts was studied. The decomposition of these Co-en species resulted in the formation of small cobalt nanoparticles. The highly dispersed catalysts led to lower FT activity due to an increase of cobalt-silica interaction except Co(en)2/SiO2 catalyst. Meanwhile, higher selectivity for light hydrocarbons was observed, which was ascribed that smaller cobalt particles containing active sites depressed the chain growth.

Synthesis of light hydrocarbons over Fe/AC catalysts

A series of Fe/AC catalysts for catalytic hydrogenation of CO to light hydrocarbons (LHCs) were prepared by decomposing Fe(CO)5 in an autoclave. The catalysts activities were tested in a high-pressure micro reactor. The results show that both CO conversion and LHCs selectivity were significantly affected by the amount of Fe loaded onto the catalysts. The optimum Fe content was determined to be 10% by weight of the catalyst. Over the corresponding catalyst (i.e., 10% Fe/C catalyst), the conversion of CO and the selectivity of LHCs were 94.8% and 59.2%, respectively, at 360°C. Based on various catalyst characterization techniques, such as XRD, BET and SEM, the catalysts surface areas and pore volume decreased and the smaller particles agglomerated at the edges and corners in the outer region of the support with the increasing Fe content. The agglomerated particles increased greatly when the iron content of the catalyst was higher than 10%. The decrease of catalyst activity can be due to the agglomerated particles.

Effects of Reaction Conditions on Cobalt-Catalyzed Fischer-Tropsch Synthesis: Interactions between Operating Factors

In Fischer-Tropsch Synthesis, because of few reactants (<TEX>$H_2$</TEX>, CO), scarce operating parameters affected on efficiency especially the selectivity of products. In this research, effect of operating parameters on the selectivity of Co-Mn-<TEX>$TiO_2$</TEX> Fischer-Tropsch synthesis catalyst were studied by design of experimental procedure and Taguchi method. According to this research, interactions between operating factors have a crucial effect on light products selectivity. Among these interactions, (temperature<TEX>${\times}$</TEX>feed ratio) has the main influence on light hydrocarbons selectivity. It was concluded that temperature and feed ratio (<TEX>$H_2$</TEX>/CO) were the most integral operating parameters for much greater selectivity of light hydrocarbons.

Synthesis of light hydrocarbons from syngas in near-critical phase

Selective synthesis of light hydrocarbons from synthesis gas (syngas) over hybrid catalysts based on the Cu–Zn oxide and Pd-β zeolite in a near-critical phase was investigated. Light hydrocarbons were directly synthesized from syngas over the catalysts through an intermediate of methanol or DME. Introduction of near-critical fluid remarkably decreased the yield of CO 2 by suppressing the water–gas shift reaction. Differences in activity, CO 2 selectivity, hydrocarbon distributions, catalyst stability and heat transfer between near-critical and conventional gas phase light hydrocarbons synthesis were compared. Efficient removal of reaction heat increased the stability of the catalysts and selectivity of light hydrocarbons in the reaction.

Use of a non-thermal plasma for the production of synthesis gas from biogas

Abstract The conversion of biogas (mixture CH 4 /CO 2 : 60/40) was studied using pulsed dielectric barrier discharges at different temperatures. The influence of the presence of a catalyst obtained after reduction of the perovskite LaNiO 3 was reported. The main products of the reaction were hydrogen and carbon monoxide, but hydrocarbons such as: C 2 H 6 , C 2 H 4 , C 2 H 2 , C 3 H 8 , trace amounts of C4 to C6, and oxygenate compounds: methanol, ethanol, and acetone, were also formed.The conversion increased with the temperature, the selectivity of light hydrocarbons (C 2 , C 3 , and C 4 ) is maximum at 673 K. When the temperature is higher than 673 K, CO production is favoured resulting most probably from the reaction between deposited carbon and an active oxygen species. The results showed that the plasma catalyst association facilitates the CO 2 activation and influences the product selectivities. It is possible to admit that the metallic nickel species react as “radicals trap”, while the basicity of the La 2 O 3 favours the activation of CO 2 increasing the CO selectivity as soon as discharge plasma are combined with the catalyst.