Combination Of Catalyst Research Articles

Electromagnetic Catalytic Cracking Process of Vacuum Residue Using Fe2O3/Al2O3

Vacuum residue well know as waste product from refinery crude oil refinery and need a further process to improve its quality. In this study, a catalytic cracking process of vacuum residue in electromagnetic field is investigated using Fe 2 O 3 /Al 2 O 3 as catalyst. The optimization process is conducted by combination vacuum residue and catalyst in the ratios of 1:5, 1:6, 1:7, 1:8, and 1:9 under 75 min of reaction time, 400 o C and 10A applied current . Liquid product analyzed using gas cromatografy mass spectrometry (GCMS). The result showed that there were a formation of, p-xylene, paraffin, and naphthalene detected, meaning it was successfully cracked. In the retention time 4,3min, identified p-xylene which aromatic groups about 11,38%. Not only 1,04% paraffin identified in the retention time 7,76 min. But also, naphtalene about 3,28% was identified in the retention time 7,80 min.

Facet-Dependent Selectivity of Cu Catalysts in Electrochemical CO2 Reduction at Commercially Viable Current Densities.

Despite substantial progress in the electrochemical conversion of CO2 into value-added chemicals, the translation of fundamental studies into commercially relevant conditions requires additional efforts. Here, we study the catalytic properties of tailored Cu nanocatalysts under commercially relevant current densities in a gas-fed flow cell. We demonstrate that their facet-dependent selectivity is retained in this device configuration with the advantage of further suppressing hydrogen production and increasing the faradaic efficiencies toward the CO2 reduction products compared to a conventional H-cell. The combined catalyst and system effects result in state-of-the art product selectivity at high current densities (in the range 100–300 mA/cm2) and at relatively low applied potential (as low as −0.65 V vs RHE). Cu cubes reach an ethylene selectivity of up to 57% with a corresponding mass activity of 700 mA/mg, and Cu octahedra reach a methane selectivity of up to 51% with a corresponding mass activity of 1.45 A/mg in 1 M KOH.

Potentiality of combined catalyst for high quality bio-oil production from catalytic pyrolysis of pinewood using an analytical Py-GC/MS and fixed bed reactor

The aim of this study was to investigate the potential of combined catalyst (ZSM-5 and CaO) for high quality bio-oil production from the catalytic pyrolysis of pinewood sawdust that was performed in Py-GC/MS and fixed bed reactor at 500 °C. In Py-GC/MS, the maximum yield of aromatic hydrocarbon was 36 wt% at biomass to combined catalyst ratio of 1:4 where the mass ratio of ZSM-5 to CaO in the combined catalyst was 4:1. An increasing trend of phenolic compounds was observed with an increasing amount of CaO, whereas the highest yield of phenolic compounds (31 wt%) was recorded at biomass to combined catalyst ratio of 1:4 (ZSM-5: CaO - 4:1). Large molecule compounds could be found to crack into small molecules over CaO and then undergo further reactions over zeolites. The water content, higher heating value, and acidity of bio-oil from the fixed bed reactor were 21%, 24.27 MJkg−1, and 4.1, respectively, which indicates that the quality of obtained bio-oil meets the liquid biofuel standard ASTM D7544-12 for grade G biofuel. This research will provide a significant reference to produce a high-quality bio-oil from the catalytic pyrolysis of woody biomass over the combined catalyst at different mass ratios of biomass to catalyst.

Metal-organic coordination polymer-derived carbon nanotubes: Preparation and application in detecting small molecules

Two new isostructural metal–organic coordination polymers (MOCPs) based on the bis-pyridyl-bis-amide ligand and thiophene dicarboxylic acid, namely [Cd(3-dpaa)0.5(2,5-TDC)(H2O)2] (1) and [Zn(3-dpaa)0.5(2,5-TDC)(H2O)2] (2) (3-dpaa = N,N′-di(3-pyridyl)adipoamide and 2,5-H2TDC = 2,5-thiophenedicarboxylic acid), have been hydrothermally synthesized and structurally characterized. The fluorescent sensing behaviors of complex 2 have been studied. Moreover, complex 2 was used as a combined catalyst precursor to synthesize multi-walled carbon nanotubes (MWCNTs). The decomposition of ethylene in the presence of the Zn-MOCP by the chemical vapor deposition (CVD) method at 650 °C led to successful obtain as-grown MWCNT products. Interestingly, the as-grown MWCNTs exhibit significant fluorescent sensing activities towards xylene and nitrobenzene.

Catalytic Methylation of Aromatic Hydrocarbons using CO2/H2 over Re/TiO2 and H‐MOR Catalysts

AbstractA combined catalyst comprising TiO2‐supported Re (Re(1)/TiO2; Re=1 wt%) and H‐MOR (SiO2/Al2O3=90) was found to promote the methylation of benzene using CO2 and H2. This catalytic system exhibited high performance with regard to the synthesis of methylated benzenes and gave high yields of total methylated products (up to 52 % benzene‐based yield and 42 % CO2‐based yield) under the reaction conditions employed in this study (pCO2=1 MPa; pH2=5 MPa; T=250 °C; t=20 h) in a batch reactor. Catalyst screening demonstrated that a combination of Re(1)/TiO2 and H‐MOR (SiO2/Al2O3=90) exhibited superior performance compared to other combinations of supported metal catalysts and zeolites in terms of both yield and selectivity for methylated benzenes.

Renewable Aliphatic Polyesters from Fatty Dienes by Acyclic Diene Metathesis Polycondensation

AbstractThree renewable, linear, aliphatic polyesters were prepared by Acyclic diene metathesis (ADMET) polymerization of α,ω‐dienes derived from fatty acids. Condensation of 9‐decenoic acid with allyl 9‐decenoate, ethylene glycol, and 9‐decen‐1‐ol proceeded in high conversion (≥94%) and purity (>99%) to give α,ω‐dienes suitable for subsequent polycondensation. Polymerization was achieved using 1.0 mol% Hoveyda‐Grubbs second‐generation metathesis catalyst in combination with 2.0 mol% 2,6‐dichloro‐1,4‐benzoquinone as an isomerization inhibitor under vacuum to drive equilibria toward polymer formation via ethene removal. Polymerization in the presence of solvent promoted ring‐closing metathesis (RCM) at the expense of polymer, with cyclization increasing as the concentration of monomer decreased. Thus, ADMET polymerizations were performed in bulk to mitigate RCM. The resulting polymers with M n and Ð that ranged from 6.6 to 8.9 kDa and 1.75–2.14, respectively, contained 76% or more of renewable carbon content and exhibited atom and carbon economies of greater than 84%. Melt (T m) and crystallization (T c) temperatures were 20.8–48.4 °C and 3.8–37.6 °C, respectively, and increased as ester density decreased within polymer structures. Sub‐ambient glass transitions ranged from −10.3 to −50.0 °C. Lastly, the polymers were thermally stable below 320 °C, as 10% mass loss (T10) occurred above 340 °C, which indicated that they existed as liquids for at least 319 °C (T10 − T m) before decomposing.

Tuning morphology and structure of Fe–N–C catalyst for ultra-high oxygen reduction reaction activity

Exploring efficient and durable non-precious metal catalysts for oxygen reduction reaction (ORR) has long been pursued in the field of metal-air batteries, fuel cells, and solar cells. Rational design and controllable synthesis of desirable catalysts are still a great challenge. In this work, a novel approach is developed to tune the morphologies and structures of Fe–N–C catalysts in combination with the dual nitrogen-containing carbon precursors and the gas-foaming agent. The tailored Fe–N1/N2–C-A catalyst presents gauze-like porous nanosheets with uniformly dispersed tiny nanoparticles. Such architectures exhibit abundant Fe-Nx active sites and high-exposure surfaces. The Fe–N1/N2–C-A catalyst shows extremely high half-wave potential (E1/2, 0.916 V vs. RHE) and large limiting current density (6.3 mA cm−2), far beyond 20 wt% Pt/C catalyst for ORR. This work provides a facile morphological and structural regulation to increase the number and exposure of Fe-Nx active sites.

Catalytic Technologies for CO Hydrogenation for the Production of Light Hydrocarbons and Middle Distillates

In South Korea, where there are no resources such as natural gas or crude oil, research on alternative fuels has been actively conducted since the 1990s. The research on synthetic oil is subdivided into Coal to Liquid (CTL), Gas to Liquid (GTL), Biomass to Liquid (BTL), etc., and was developed with the focus on catalysts, their preparation, reactor types, and operation technologies according to the product to be obtained. In Fischer–Tropsch synthesis for synthetic oil from syngas, stability, CO conversion rate, and product selectivity of catalysts depends on the design of their components, such as their active material, promoter, and support. Most of the developed catalysts were Fe- and Co-based catalysts and were developed in spherical and cylindrical shapes according to the reactor type. Recently, hybrid catalysts in combination with cracking catalysts were developed to control the distribution of the product. In this review, we survey recent studies related to the design of catalysts for production of light hydrocarbons and middle distillates, including hybrid catalysts, encapsulated core–shell catalysts, catalysts with active materials with well-organized sizes and shapes, and catalysts with shape- and size-controlled supports. Finally, we introduce recent research and development (R&D) trends in the production of light hydrocarbons and middle distillates and in the catalytic processes being applied to the development of catalysts in Korea.

An effective combination catalyst of CeO2 and zeolite for the direct synthesis of diethyl carbonate from CO2 and ethanol with 2,2-diethoxypropane as a dehydrating agent

The combination of CeO2 and H-FAU zeolite acted as an effective heterogeneous catalyst for the direct synthesis of diethyl carbonate from CO2 and ethanol with 2,2-diethoxypropane as a dehydrating agent.

Electro-derived Cu-Cu2O nanocluster from LDH for stable and selective C2 hydrocarbons production from CO2 electrochemical reduction

Recently, CO 2 conversion by electrochemical tool into value-added chemicals has been considered as one of the most promising strategies to offer sustainable development in energy and environment. In this contribution, we investigated electro-derived composites from Cu-based layered double hydroxide (LDH) for CO 2 electrochemical reduction. The Cu-Cu 2 O based nanocomposite (HPR-LDH) were derived by using electro-strategy from LDH having the stability up to 20 h and selectivity toward C 2 H 4 with faraday efficiency up to 36% by significantly suppressing CH 4 and H 2 with respect to bulk Cu foil. A highly negative reduction potential derived catalyst (HPR-LDH) maintained long-term stability for the selective production of ethylene over methane, and a small amount of Cu 2 O was still observed on the catalyst surface after CO 2 reduction reaction (CO 2 RR). Moreover, such unique strategy for electro-derived composite from LDH having small nanoparticles stacked each other grown on layered structure, would provide new insight to improve durability of O Cu combination catalysts for C C coupling products during electrochemical CO 2 conversion by suppressing HER. The XRD, SEM, ESR, and XPS analyses confirmed that the long-term ethylene selectivity of HPR-LDH is due to the presence of subsurface oxygen. The designed composite catalyst significantly enhances the stability and selectivity, and also decreases the over potential for CO 2 electro-reduction. We predict that the new designed LDH 2D-derived composites may attract new insight for transition metal and may open up a new direction for known structural properties of selective catalyst synthesis regarding effective CO 2 reduction reaction. A new type of electro-catalysts derived from layer double hydroxides for CO 2 electrochemical reduction into C 2 hydrocarbon was developed, which exhibited outstanding CO 2 electrochemical reduction capacity, high faradic efficiency products selectivity and excellent production stability.

Palladium-Catalyzed Dual Ligand-Enabled Alkylation of Silyl Enol Ether and Enamide under Irradiation: Scope, Mechanism, and Theoretical Elucidation of Hybrid Alkyl Pd(I)-Radical Species

We report herein that a palladium catalyst in combination with a dual phosphine ligand system catalyzes alkylation of silyl enol ether and enamide with a broad scope of tertiary, secondary, and pri...

Co-pyrolysis of biomass and plastic waste over zeolite- and sodium-based catalysts for enhanced yields of hydrocarbon products

Ex-situ co-pyrolysis of sugarcane bagasse pith and polyethylene terephthalate (PET) was investigated over zeolite-based catalysts using a tandem micro-reactor at an optimised temperature of 700 °C. A combination of zeolite (HZSM-5) and sodium carbonate/gamma-alumina served as effective catalysts for 18% more oxygen removal than HZSM-5 alone. The combined catalysts led to improved yields of aromatic (8.7%) and olefinic (6.9%) compounds. Carbon yields of 20.3% total aromatics, 18.3% BTXE (benzene, toluene, xylenes and ethylbenzene), 17% olefins, and 7% phenols were achieved under optimal conditions of 700 °C, a pith (biomass) to PET ratio of 4 and an HZSM-5 to sodium carbonate/gamma-alumina ratio of 5. The catalytic presence of sodium prevented coke formation, which has been a major cause of deactivation of zeolite catalysts during co-pyrolysis of biomass and plastics. This finding indicates that the catalyst combination as well as biomass/plastic mixtures used in this work can lead to both high yields of valuable aromatic chemicals and potentially, extended catalyst life time.

Ultrasonic-assisted degradation of a triarylmethane dye using combined peroxydisulfate and MOF-2 catalyst: Synergistic effect and role of oxidative species

Combination of various advanced oxidations processes (AOPs) for effective water treatment is significant from a practical viewpoint. In this study, metal-organic framework-2 (MOF-2) nanomaterial (NM) was synthesized and then coupled with ultrasound (US) process in the presence of peroxydisulfate (S2O82−) for Acid Blue 7 (AB7) degradation as a triarylmethane model dye. The XRD, FT-IR, SEM, TEM, BET, and DRS analyses were utilized to confirm the appropriate formation of nanoporous flake-like MOF-2 with a high specific surface area of 942.6 m2/g. The combined US/MOF-2/S2O82− process demonstrated the highest performance compared to the US and US/S2O82− processes in the same operational conditions. The mentioned processes obeyed pseudo-first-order kinetic and their synergistic effect for the AB7 degradation was determined according to the obtained apparent rate constants (kapp) as 63.4%. Radical quenching experiments using various scavengers revealed the oxidative species role for the AB7 treatment, which were generated during the sonolysis and sonolycatalytic process in the presence of the S2O82− based on the hot spot explanation. Consequently, the dominant reactive species were hydroxyl (OH), sulfate (SO4-), superoxide (O2-) and singlet oxygen (1O2) radicals. The GC–MS method was carried out to identify the main degradation intermediates, and five intermediates were detected.

Enantioselective Kinetic Resolution/Desymmetrization of Para-Quinols: A Case Study in Boronic-Acid-Directed Phosphoric Acid Catalysis.

A chiral phosphoric acid-catalyzed kinetic resolution and desymmetrization of para-quinols operating via oxa-Michael addition was developed and subsequently subjected to mechanistic study. Good to excellent s-factors/enantioselectivities were obtained over a broad range of substrates. Kinetic studies were performed, and DFT studies favor a hydrogen bonding activation mode. The mechanistic studies provide insights to previously reported chiral anion phase transfer reactions involving chiral phosphate catalysts in combination with boronic acids.

Hydrogenation of Polyesters to Polyether Polyols.

The amount of plastic waste is continuously increasing. Besides conventional recycling, one solution to deal with this problem could be to use this waste as a resource for novel materials. In this study, polyesters are hydrogenated to give polyether polyols by using in situ‐generated Ru‐Triphos catalysts in combination with Lewis acids. The choice of Lewis acid and its concentration relative to the ruthenium catalyst are found to determine the selectivity of the reaction. Monitoring of the molecular weight during the reaction confirms a sequential mechanism in which the diols that are formed by hydrogenation are etherified to the polyethers. To probe the applicability of this tandem hydrogenation etherification approach, a range of polyester substrates is investigated. The oligoether products that form in these reactions have the chain lengths that are appropriate for application in the adhesives and coatings industries. This strategy makes polyether polyols accessible that are otherwise difficult to obtain from conventional fossil‐based feedstocks.

Long-acting photocatalytic degradation of crude oil in seawater via combination of TiO2 and N-doped TiO2/reduced graphene oxide

ABSTRACT N-doped TiO2/ reduced graphene oxide (N/TiO2/rGO) composite was prepared and used together with the commercial TiO2 for comparative research on photocatalytic degradation of crude oil in seawater. Five test conditions were designed including a combined catalyst of TiO2 and N/TiO2/rGO (4:1) under UV-A light irradiation with a duration of 28 days. The changing trend of the water-soluble fraction (WSF) of crude oil in seawater was monitored by ultraviolet spectroscopy and fluorescence spectroscopy as well as dissolved organic carbon (DOC) measurement. The SARA fractions of oil residues were analysed by column chromatography, and the chemical composition changes of saturates and aromatics were investigated by gas chromatography-mass spectroscopy (GC-MS). The results reveal that although it had high efficiency in the degradation of aromatics, the nano-TiO2 tended to self-agglomerate, which enhanced agglomeration of crude oil, causing its catalytic process actually terminating within seven days. By comparison, the N/TiO2/rGO composite consistently dispersed crude oil in the whole experimental duration, subsequently, it presented a higher photocatalytic degradation rate than TiO2. The combination of TiO2 and N/TiO2/rGO (4:1) shows concerted catalysis on photocatalytic degradation of crude oil, and the oil degradation rate reached to 54.80% while the aromatic degradation rate was 74.83%. The fluorescent components in WSFs were preferentially degraded, and the degradation products of aromatic fraction were CO2 and H2O as well as saturates, mainly C20∼C31 alkanes. Considering its long-acting photocatalysis, the N/TiO2/rGO composite possesses practical utilization potentiality together with TiO2 in spilled oil treatment in the marine environment.

Stereo-polymerization of 1,3-Butadiene by Cobalt Catalysts in the Presence of External Donor: Access to 1,2-Syndiotactic Polybutadiene with Tunable Properties

Disulfide carbon (CS2) and triphenyl phosphine (TPP) were tested as donors for cobalt (Co1, Co2, and Co3)-catalyzed 1,2-syndiotactic polymerization of butadiene. With CS2, a 1,2-selectivity of 96.8% and syndiotacticity (rr) up to 97% were achieved by Co1–Co3/AliBu3/CS2, yielding highly crystallized polybutadiene resin. Variations on polymerization temperature (0–80 °C), catalyst loading, and polymerization time did not significantly affect the 1,2-incorporation and syndiotactic conformation of the resulting polymers, highlighting the excellent 1,2-stereoselectivity of active species stabilized by CS2. With external donor TPP, the formed Co1–Co3/MAO/TPP have regioselectivities of 65.2–89.2% and syndiotacticities of 32.1–65.5%. Thus, an array of polybutadienes differing in chemoenchainment and 1,2-stereoenchainment is accessible with the present cobalt catalysts in combination with different donors. AFM measurements were performed to distinguish the morphology of two types of 1,2-syn-polybutadiene. Elucidat...

Glucose-based carbon materials as supports for the efficient catalytic transformation of cellulose directly to ethylene glycol

Glucose-derived carbon materials were synthesized and used to support Ru–W bimetallic catalysts that provide the one-pot conversion of cellulose to ethylene glycol (EG). The catalysts prepared on the carbonized glucose (after hydrothermal synthesis and carbonization) were the most efficient for the production of EG, with yields around 30% after 5 h. Moreover, the addition of oxygenated groups to the carbon material surface enhanced the yield of EG (48% after 3 h), possibly as a result of the preferential hydrolysis of cellulose to glucose and suppressing of glucose isomerization to fructose. Furthermore, the catalytic system showed excellent stability after repeated uses, at least up to three cycles. As a result, the synthesized catalysts seem to be promising alternatives in order to produce EG directly from cellulose by a more economical (supports derived from biomass), faster (one-pot reaction) and easier (combined catalyst synthesis) process. Glucose-derived carbon materials were presented as efficient and cheaper alternatives to carbon nanotubes as supports of Ru–W catalysts for the production of EG directly from cellulose.

Synthesis of β-hydroxyamides through ruthenium-catalyzed hydration/transfer hydrogenation of β-ketonitriles in water: Scope and limitations

A cascade process for the straightforward one-pot conversion of β-ketonitriles into β-hydroxyamides is presented. The process, that proceeds in water employing the arene-ruthenium(II) complex [RuCl2(η6-p-cymene){P(4-C6H4F)2Cl}] as catalyst in combination with sodium formate, involves the initial hydration of the β-ketonitrile substrates to generate the corresponding β-ketoamide intermediates, which subsequently undergo the transfer hydrogenation (TH) of the carbonyl group. Employing a family of forty different β-ketonitriles, featuring diverse substitution patterns, the scope and limitations of the process have been established.

Nanostructured Cobalt-Containing Carbon Supports for New Platinum Catalysts

Materials containing from 3.1 to 7.7 wt % of cobalt were obtained by electrodeposition of cobalt on Vulcan XC72 carbon powder in suspension. The composition and average diameter of CoO crystallites formed as result of cobalt oxidation in the process of filtering and drying materials, depending on the electrolysis conditions and electrolyte composition, were studied using thermogravimetry and XRD. It is shown that the maximum amount of cobalt can be deposited from electrolytes containing, along with cobalt sulfate, additives of copper and nickel sulfates. Calculations by the Scherrer equation showed that an increase in the CoO content leads to a decrease in the diameter of crystallites, the size of which is in the nano-range. The analysis of X-ray and electrochemical studies indicates the formation, in the course of the borohydride’s synthesis, of combined catalysts containing nanoparticles of the Pt3Co solid solution. The best PtCo/C material demonstrated significant improvement in ORR activity and superior stability compared to commercial Pt/C catalyst of the same platinum loading.