Catalyst Precursor Research Articles

Mental Health and Information Technology Catalysts as Determinants of Innovative Work Behavior

Interpersonal interactions, such as impromptu face-to-face workplace conversations, facilitate knowledge transfer and spur innovation within individual work roles; however, the move to remote work during the COVID-19 pandemic disrupted these dynamics. This research examines how innovation can be maintained in remote work settings by considering Information Technology (IT) catalysts (a combination of IT mindfulness, IT identity, and IT empowerment) during disruptive events and crises. We also highlight the importance of remote workers’ mental health and coping as precursors for IT catalysts to stimulate innovative work behaviors. Our paper contributes to information systems (IS) theory by establishing remote workers’ mental health and coping as distal factors of innovation and precursors to IT catalysts. In addition, we extend IS theory by establishing the relationships among the IT catalyst factors as well as their impact on innovative work behaviors. Our research provides insights for organizations interested in sustaining innovation, especially during crises or other stress-inducing events or conditions.

Preparation of Nickel 2‑Ethylhexanoate, a Precursor of Cracking Catalysts for Heavy Hydrocarbon Feedstocks

Preparation of Nickel 2‑Ethylhexanoate, a Precursor of Cracking Catalysts for Heavy Hydrocarbon Feedstocks

Substrate self-derived porous rod-like NiS/Ni9S8/NF heterostructures as efficient bifunctional electrocatalysts for overall water splitting.

A self-derivation strategy using conductive substrates is used to prepare one-piece highly efficient bifunctional electrodes, where the chosen substrate acts as both an active catalyst precursor and a conductive carrier. Here, a bifunctional catalyst, porous NiS/Ni9S8/NF-2 nanorods, was synthesized by low-temperature vulcanization after an oxalic acid etching process. To reach a current density of 10 mA cm-2, NiS/Ni9S8/NF-2 requires only a tiny overpotential of 115 mV for the HER and 176 mV for the OER, and demonstrates sustained activity for 100 hours with almost any degradation. The substrate self-derived NiS/Ni9S8/NF-2 catalyst for overall water splitting requires only a small voltage of 1.52 V to deliver 10 mA cm-2 with excellent stability. Experimental results show that the heterostructured electrocatalysts impart good catalytic properties of NiS/Ni9S8/NF-2 by modulating the electronic structure and promoting the reconstruction process from sulfides to hydroxides. This work demonstrates the success of the substrate self-derivation strategy to achieve high catalytic activity and provide a new autogenous growth technique for electrode fabrication.

Iridium-(κ2-NSi) catalyzed dehydrogenation of formic acid: effect of auxiliary ligands on the catalytic performance.

The iridium(III) complexes [Ir(H)(Cl)(κ2-NSitBu2)(κ2-bipyMe2)] (2) and [Ir(H)(OTf)(κ2-NSitBu2)(κ2-bipyMe2)] (3) (NSitBu2 = {4-methylpyridine-2-yloxy}ditertbutylsilyl) have been synthesized and characterized including X-ray studies of 3. A comparative study of the catalytic activity of complexes 2, 3, [Ir(H)(OTf)(κ2-NSitBu2)(coe)] (4), and [Ir(H)(OTf)(κ2-NSitBu2)(PCy3)] (5) (0.1 mol%) as catalysts precursors for the solventless formic acid dehydrogenation (FADH) in the presence of Et3N (40 mol%) at 353 K has been performed. The highest activity (TOF5 min ≈ 3260 h-1) has been obtained with 3 at 373 K. However, at that temperature the FTIR spectra show traces of CO together with the desired products (H2 and CO2). Thus, the best performance was achieved at 353 K (TOF5 min ≈ 1210 h-1 and no observable CO). Kinetic studies at variable temperature show that the activation energy of the 3-catalyzed FADH process is 16.76 kcal mol-1. Kinetic isotopic effect (5 min) values of 1.6, 4.5, and 4.2 were obtained for the 3-catalyzed dehydrogenation of HCOOD, DCOOH, and DCOOD, respectively, at 353 K. The strong KIE found for DCOOH and DCOOD evidenced that the hydride transfer from the C-H bond of formic acid to the metal is the rate-determining step of the process.

Di-ruthenium complexes of 1,4-diazabutadiene ligands: synthesis, characterization and utilization as catalyst precursors for the oxidative coupling of amines to imines in air

A group of tri-chloro bridged di-ruthenium(ii) complexes, bearing chelated 1,4-diazabutadienes, served as efficient catalyst-precursors for the oxidative and deaminative C–N coupling of primary amines to imines using aerial oxygen as the oxidant.

Efficient additive-free formic acid dehydrogenation with a NNN-ruthenium complex.

A new ruthenium complex containing a pyridylidene amine-based NNN ligand was developed as a catalyst precursor for formic acid dehydrogenation, which, as a rare example, does not require basic additives to display high activity (TOF ∼10 000 h-1). Conveniently, the complex is air-stable, but sensitive to light. Mechanistic investigations using UV-vis and NMR spectroscopic monitoring correlated with gas evolution profiles indicate rapid and reversible protonation of the central nitrogen of the NNN ligand as key step of catalyst activation, followed by an associative step for formic acid dehydrogenation.

Heterometallic Ru–Ir carbonyl clusters as catalyst precursors for hydrogenation and hydrogen transfer reactions

Heterometallic Ru–Ir hydride carbonyl clusters were synthesized and tested as catalyst precursors for hydrogenation of 4-fluoroacetophenone and trans-cinnamaldehyde.

Preparation and properties of alumina-carbon castables using SiC nanofiber coated graphite flake

SiC nanofiber coated graphite flakes were fabricated at a relatively low temperature of 1623 K via an in-situ catalytic reaction approach employing Co(NO3)2·6H2O as a catalyst precursor. The effects of catalyst amount and firing temperature on phase composition, morphology and water wettability of the as-prepared SiC nanofiber coated graphite flakes were studied. The Co catalyst promoted the growth of SiC nanofibers, which according to the density functional theory calculations, can be attributed to the increased bond length and weakened bonding of CO(g) and SiO(g) molecules upon their adsorption onto the Co catalyst. The water contact angle of SiC nanofiber coated graphite was reduced to 25° from that 111° in the case of its uncoated counterpart. Furthermore, Al2O3-C castables using SiC nanofiber coated graphite flakes exhibited 73.1 % higher residual CMOR ratio after thermal shock test, 20.0 % lower in oxidation, and 43.5 % less in slag corrosion, than their counterparts using uncoated graphite flakes.

SYNTHESIS OF NOVEL BIS(PHOSPHINO)AMINE-RUII(ACAC)2 COMPLEXES, AND INVESTIGATION OF CATALYTIC ACTIVITY IN TRANSFER HYDROGENATION

In this study, reactions of (PPh2)2NCH2CH2N(PPh2)2 (L1) and {(PPh2)2NCH2CH2}3N (L2) with [RuII(acac)2(CH3CN)2] led to the production of new dinuclear complex [Ru(acac)2]2(L1) (1) and trinuclear complex [Ru(acac)2]3(L2) (2). Complex 1 and 2 are excellent candidates for the role of catalyst precursors in the transfer hydrogenation (TH) of acetophenone and its derivatives. Compared to complex (1), the trinuclear complex (2) is an exceptional catalyst, producing the corresponding alcohols in 98–99% yields in 20 minutes at 80 oC (TOF≤300 h-1) for the TH process. A comparison of the catalytic properties of the complexes is also briefly discussed. Complex structures have also been characterized by combining nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), and elemental analysis.

Nickel phase deposition on V2CTx/V2AlC as catalyst precursors for a dry methane reforming: The effect of the deposition method on the morphology and catalytic activity

Dry reforming of methane (DRM) is a promising alternative technology for the production of syngas with simultaneous utilization of two main greenhouse gases (CH4, CO2). However, DRM technology is still an industrially immature process due to the lack of stable and active catalyst. Therefore, the search for new catalytic materials is of great research interest. Recently, MAX and MXenes materials are increasingly being tested as potential materials for catalytic processes including dry reforming of hydrocarbons. However, transition metal carbides may be deactivated under DRM conditions due to phase transition caused by an oxidation process. The combining of the MAX/MXene materials with nickel phase may be beneficial for to improve catalytic activity and stability. In this view, we report preparation and characterization of nickel-modified V2CTx/V2AlC materials. The Ni–V2CTx/V2AlC catalysts were prepared using HF-etching followed by impregnation/precipitation method. The effect of preparation route on morphology and catalytic activity was investigated. The properties of fresh and spent catalysts were evaluated using XRD, XPS, MP-AES, SEM, BET surface area, H2-TPR, CO2-TPD, TG/DTG and TEM techniques. Catalytic activity was investigated in the DRM process at 800 °C and 1 bar. It was found that the V2CTx/V2AlC- based materials undergo phase transition to vanadium oxide V2O3, vanadium carbide V8C7 and aluminium oxide. The presence of nickel was crucial for the catalyst activity of V2CTx/V2AlC- based catalysis. The catalytic activity was different and related to the preparation procedure resulting in dissimilar nickel-phase morphology and intercalation of sodium ions. It was found that the distribution of nickel phase and presence of alkali ions determined catalysts’ activity and stability. The highest activity and stability in DRM process was observed for Ni–V2CTx/V2AlC_IMP catalysts obtained using only impregnation method without precipitation agents. For the catalysts nickel phase was distributed uniformly forming needle-like structures. The CO2 and CH4 conversions during 20 h-test were in the range of 90–93% and 90-80%, respectively. The molar ration of H2 to CO in outlet stream fluctuated from 1.05 in the first hour of the process to 0.95 after 20 h of the DRM. The activity and stability of Ni–V2CTx/V2AlC_IMP catalyst was higher compared to unmodified V2CTx/V2AlC, unetched V2AlC and Ni–SiO2.

Preparation of benzoxazoles and benzothiazoles utilizing naturally occurring copper-containing mineral catalyst precursors

Copper is one of the most abundant metals on Earth, and although it is mainly used in other fields, copper catalysis is also widely used in preparative organic syntheses. As copper production has recently exceeded a yearly amount of 20 million tons, using minerals instead of pure copper compounds can lower the need for such processes and can lead to more economical and environmentally friendly procedures. Such a method is the subject of our present study in which the preparation of 2-substituted benzoxazoles and benzothiazoles is presented from inexpensive starting materials in a simple setup, in the presence of naturally occurring copper-containing minerals. A total of 7 readily available minerals were tested in our model reaction and the reaction was feasible with all of them. With our method, a wide variety of benzoxazoles and benzothiazoles were prepared in good yields and high purity. The reaction could be carried out regardless of the origin of the minerals.

Ethylene Dimerization and Oligomerization Using Bis(phosphino)boryl Supported Ni Complexes

We report the dimerization and oligomerization of ethylene using bis(phosphino)boryl supported Ni(II) complexes as catalyst precursors. By using alkylaluminum(III) compounds or other Lewis acid additives, Ni(II) complexes of the type (RPBP)NiBr (R = tBu or Ph) show activity for the production of butenes and higher olefins. Optimized turnover frequencies of 640 molethylene·molNi-1·s-1 for the formation of butenes with 41(1)% selectivity for 1-butene using (PhPBP)NiBr, and 68 molethylene·molNi-1·s-1 for butenes production with 87.2(3)% selectivity for 1-butene using (tBuPBP)NiBr, have been demonstrated. With methylaluminoxane as a co-catalyst and (tBuPBP)NiBr as the precatalyst, ethylene oligomerization to form C4 through C20 products was achieved, while the use of (PhPBP)NiBr as the pre-catalyst retained selectivity for C4 products. Our studies suggest that the ethylene dimerization is not initiated by Ni hydride or alkyl intermediates. Rather, our studies point to a mechanism that involves a cooperative B/Ni activation of ethylene to form a key 6-membered borametallacycle intermediate. Thus, a cooperative activation of ethylene by the Ni-B unit of the (RPBP)Ni catalysts is proposed as a key element of the Ni catalysis.

High activity and strong coke resistance of nickel CO2-CH4 reforming catalyst promoted by different plasma treated modes

The radio frequency plasma was used to decorate the MCM-41 support or to treat the catalyst precursor. The structures and CO2CH4 reforming performances of nickel-based catalysts prepared by different plasma treated modes were compared. The catalysts were characterized by XRD, FT-IR, H2-TPR, XPS, TEM, TG and contact angle. Comparing with the calcined catalyst supported on common MCM-41 (N-M-C), the plasma treated catalyst supported on plasma decorated MCM-41(N-MP-P) showed highest activity and best stability because of less Si-OH groups on support, smaller nickel particle size and more homogeneously dispersion as well as stronger interaction between nickel-MCM-41. The average CH4 and CO2 conversions were increased by 24.0% and 19.3%, respectively. After 30 h reaction, there was a little loss of the conversions, and the carbon deposition was decreased from 35.8% on N-M-C to 0.8% on N-MP-P; additionally, the Ni particle size was reduced from 20.9 to 8.5 nm, which proved that the coke resistance was apparently promoted. Comparing with the effect of plasma decorating the support, that of plasma treating the catalyst precursor played a more important role in the structure and catalytic performance of the Ni-based catalyst.

Ultralow Pt Catalyst Loading Prepared by the Electroreduction of a Supramolecular Assembly for the Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) from the electrocatalysis of water splitting is the most promising approach to producing green and renewable hydrogen energy for sustainable development. The precious metal platinum is the best electrocatalyst for HER. However, its scarcity and high cost still hinder the large-scale application. It is highly desirable to fabricate efficient Pt electrocatalysts with low Pt loading. Herein, we report an efficient ultralow Pt-loading HER catalyst, which was obtained by the electroreduction of a preprepared supramolecular self-assembly. Utilizing the strong hydrogen bonding formation ability of macrocyclic cucurbit[8]uril (CB[8]), a porous supramolecule (CB[8]-[PtCl6]) composed of [PtCl6]2– and CB[8] is obtained as the HER catalyst precursor. By the electroreduction of the as-prepared supramolecular compound, Pt nanoparticles (NPs) protected by CB[8] (CB[8]-Pt) exhibit high catalytic activity and excellent long-term stability toward HER with ultralow Pt loading. CB[8]-Pt with a Pt loading of only 1.2 μg/cm2 presents 23 times higher HER activity than commercial Pt/C. Moreover, CB[8]-Pt shows excellent stability under 10 000-cycle cyclic voltammetry (CV) and at least 120 h for chronopotentiometry at 10 mA/cm2 in 0.5 M H2SO4, which greatly outperforms commercial Pt/C. This work provides a strategy for the rational design of ultralow-loading Pt catalysts with good activity and stability for hydrogen production.

Crystalline multilayer graphene nanoflakes synthesized by catalytic chemical vapor deposition using reduced nanostructured hematite as catalyst precursor and 1,2-dichlorobenzene and benzylamine mixture as carbon source

Carbon solubility in the catalyst for the growth of graphene-type nanomaterials is an essential issue for their large-scale fabrication. Iron compounds are fundamental catalysts for the synthesis of carbon materials. The carbon solubility of ferrite (α-Fe) is ∼0.1% at 700 °C, which is enough to promote the growth of graphene nanomaterials. In this work, we synthesized crystalline multilayer graphene flakes (MLGFs) by a two-step catalytic chemical vapor deposition method using an α-Fe catalyst derived from the reduction of nanostructured hematite at 950 °C under an Ar–H2 environment. In the first step, nitrogen-doped multi-walled carbon nanotubes were synthesized by a benzylamine-ferrocene mixture at 850 °C and oxidized at 620 °C in air. In the second step, the reduced nanostructured hematite was exposed to a mixture of a 1:9 benzylamine-1,2- dichlorobenzene at 950 °C. Raman spectroscopy confirmed the presence of MLGFs with a G band and a significant 2D band intensity. The results of the thermogravimetric analysis show that the maximum oxidation rate was at 643.5 °C. Additional functional density calculations were performed considering graphene growth on the oriented (110) α-Fe surface. This work reasserts the possibility of using alternative carbon sources for graphene growth.

Highly individual single-walled carbon nanotubes synthesized by floating catalyst chemical vapor deposition for transparent conducting films

The bundle formation of single-walled carbon nanotubes (SWCNTs) has dramatically hindered their performances of transparent conducting films (TCFs). Herein, we synthesized less bundled SWCNTs by reducing the concentration of catalyst precursor in floating catalyst chemical vapor deposition. The gas-phase number concentration of SWCNTs could be reduced from 1.6×106 to 4×105 cm−3 by decreasing the catalyst precursor and thus, the bundle formation due to nanotube collisions induced by Brownian diffusion was significantly inhibited. ∼42% of SWCNTs were found to be individual with a mean tube diameter of 1.0 nm, mean length of 2.5 μm and mean bundle diameter of 2.1 nm, the corresponding SWCNT TCF exhibited a sheet resistance of 109 Ω/sq. at 90% optical transmittance. Our work provides a strategy of synthesizing highly individual SWCNTs for enhanced performance of TCFs, implying great potential in electronic applications.

Ultrathin NiZrAl layered double hydroxide nanosheets derived catalyst for enhanced CO2 methanation

It is challenging to fabricate supported Ni catalysts with more active sites to improve their low-temperature catalytic performance in CO2 methanation. Herein, firstly, ultrathin (∼4 nm) NiZrAl layered double hydroxide (LDH) nanosheets were synthesized by co-precipitation method, followed by aqueous miscible organic solvent treatment (AMOST), and applied as catalyst precursors for CO2 methanation. After H2 reduction, the surface area of Ni particles in NiZrAl-LDH-AMO-R was significantly higher than that of NiZrAl-LDH-R without AMOST. As a result, the NiZrAl-LDH-AMO-R showed higher catalytic activity than NiZrAl-LDH-R owing to its higher H2 and CO2 chemisorption capacity and lower activation energy. During the 100 h-lifetime test, NiZrAl-LDH-AMO-R maintained a steady CO2 conversion of about 92.3%. Moreover, NiZrAl-LDH-AMO-R maintained its catalytic activity after a 600 °C-hydrothermal treatment, suggesting its high stability. In situ DRIFTS results reveal that CO2 methanation on both NiZrAl-LDH-R and NiZrAl-LDH-AMO-R followed the HCOO∗ route. Interestingly, more active sites obtained after AMOST strongly promoted the generation and decomposition of HCOO∗, and thus significantly improved the activity of NiZrAl-LDH-AMO-R at low temperatures.

Layered double hydroxides as precursors for catalysts in Claisen-Schmidt condensation

MMgAlO and MAlO mixed oxides (where M = Cu, Co, Zn and Ni) were obtained by thermal decomposition of the corresponding layered double hydroxides (LDH) precursors and used as catalysts for Claisen-Schmidt condensation of 2’-hydroxyacetophenone and benzaldehyde under solvent-free conditions. The catalysts were characterized by X-ray diffraction (XRD), atomic absorption spectrometry and temperature-programmed desorption of CO2 (TPD-CO2). Gas chromatography – mass spectroscopy (GC/MS) methods were used for the identification and quantification of the product mixture. A 2’-hydroxychalcone and 2-phenyl-2,3-dihydro-4H-chromen-4-one (flavanone) were received as main products. 3-Benzyl-2-phenyl-4H-chromen-4-one (3-benzylflavone) was achieved as a new product.

Structuring and Phase Formation in the Treatment of La/Al2O3 Catalyst Precursors in Water Fluids

Structuring and Phase Formation in the Treatment of La/Al2O3 Catalyst Precursors in Water Fluids

Modified polymer 3D printing enables the formation of functionalized micro-metallic architectures

Three-dimensional metallic microstructures have attracted a significant attention with their unique properties to be employed in a vast range of applications. However, the drawbacks of existing manufacturing technologies have prompted researchers’ interest in polymer 3D printing for the creation of complex micro 3D structures followed by metallization. Yet, the conventional metallization techniques may hinder the uniformity of metallic layer. Hence in this paper, we have established micro 3D printing with a catalyst resin which enables uniform metallization of complex microstructure surfaces through electroless deposition (ELD). The resin is infused with catalyst precursor to facilitate catalytic action required for ELD. The developed, optimized procedure of ELD with pre-treatment of structures enhances the quality of metallization through the uniform coating on both internal and external surfaces of the microstructure. As such, the technology promotes ELD of any required metal on microstructure surface with excellent surface finish, conductivity, or magnetism as required by the researcher. Furthermore, the technology is capable of manufacturing micro 3D structures of fine resolutions of few tens of micro-meters in a regular micro 3D printer. To demonstrate the application of this technique in a practical scenario, a 3D printed mini wheel was magnetized and functioned as a magnetically activated microrobot under an external magnetic field. And the proposed method displayed exceptional potential in manufacturing complex metallic micro 3D structures with excellent properties as required in an environmentally friendly way and at a significantly reduced cost for a vast range of applications. And this proved to be a much-improved alternative to the conventional techniques of manufacturing metallic micro 3D structures.