Synthesis of highly stable dual-site immobilized ruthenium olefin metathesis catalyst without ru leaching

The tri-block copolymer is used as a carrier to simultaneously immobilize the N-heterocyclic and benzylidene ligands precursor of the Ru-based catalyst to form a dual-site immobilized catalyst. The dual-site immobilized catalyst can catalyze ring-opening metathesis polymerization, ring-closing metathesis and self-metathesis. The dual-site immobilized catalyst shows good heterogeneity in dichloromethane, which simplifies the purification of product and recovery of catalyst. The dual-site immobilized catalyst exhibits excellent activity and recycling performance. The excellent recyclability can be attributed to the capture of ruthenium by the excess ligands precursor on carrier. Importantly, ruthenium residues are not detected in product.

A comparative study of the performance of zinc oxide and iron oxide doped-zinc oxide photocatalysts toward the oxidization of phenol under UV-radiation and sunlight

In the present work, a comparative analysis of the photocatalytic degradation of phenol, was done for two different types of immobilized photocatalytic nanoparticles immobilized on 5mm sodalime beads by a facile and cost-effective method: (1) Zinc oxide (ZnO) and (2) Iron doped Zinc Oxide (Fe-ZnO). Tests of phenol degradation by using the immobilized catalyst were conducted in batch photoreactors under UVA light of 22W and summertime sunlight. These tests allowed us to evaluate the phenol degradation rate and photocatalyst durability under controlled conditions.

Synthesis of a Novel Series of Cu(I) Complexes Bearing Alkylated 1,3,5-Triaza-7-phosphaadamantane as Homogeneous and Carbon-Supported Catalysts for the Synthesis of 1- and 2-Substituted-1,2,3-triazoles

The N-alkylation of 1,3,5-triaza-7-phosphaadamantane (PTA) with ortho-, meta- and para-substituted nitrobenzyl bromide under mild conditions afforded three hydrophilic PTA ammonium salts, which were used to obtain a new set of seven water-soluble copper(I) complexes. The new compounds were fully characterized and their catalytic activity was investigated for the low power microwave assisted one-pot azide–alkyne cycloaddition reaction in homogeneous aqueous medium to obtain disubstituted 1,2,3-triazoles. The most active catalysts were immobilized on activated carbon (AC), multi-walled carbon nanotubes (CNT), as well as surface functionalized AC and CNT, with the most efficient support being the CNT treated with nitric acid and NaOH. In the presence of the immobilized catalyst, several 1,4-disubstituted-1,2,3-triazoles were obtained from the reaction of terminal alkynes, organic halides and sodium azide in moderate yields up to 80%. Furthermore, the catalyzed reaction of terminal alkynes, formaldehyde and sodium azide afforded 2-hydroxymethyl-2H-1,2,3-triazoles in high yields up to 99%. The immobilized catalyst can be recovered and recycled through simple workup steps and reused up to five consecutive cycles without a marked loss in activity. The described catalytic systems proceed with a broad substrate scope, under microwave irradiation in aqueous medium and according to “click rules”.

Improved xylanase Characteristics upon enzyme entrapment Isolated from Thermomyces lanuginosus C9

Xylanases from microbial sources assume basic jobs in an assortment of industrial applications as a biocatalyst, and its applications generally require immobilization on supports to upgrade their stability. Enzyme immobilization is a thrilling decision to show signs of improved strength of enzymatic procedures. In this work, two sorts of polymeric backings (agar-agar and calcium alginate) are utilized to immobilize β-1,4-xylanase from Thermomyces lanuginosus C9 by entrapment, and afterward, biochemical properties of the entangled enzymes were performed. To create immobilized catalyst beads centralization of 4% agar while mix of sodium alginate 5% and calcium chloride 0.4 M was seen as ideal. Ideal reaction time for agar and calcium alginate immobilized protein increments from 10 to 25 and 30 min, separately. The incubation temperature expanded from 70°C to 75°C for agar however stayed unaltered for calcium alginate. The pH profile of free and immobilized xylanase was generally equal in both cases. Be that as it may, both the strategies changed the active boundaries of immobilized β-1,4-xylanase rather than free protein. High sub-atomic load of xylan limits dispersion which brings down the Vmax estimation of immobilized protein while Km value expanded. In contrast with agar-agar, protein immobilized inside calcium alginate display wide thermal stability and kept up 86.6% of its underlying activity at 80°C up to 150 min. Be that as it may, biotechnological portrayal demonstrated that the catalyst reusability was the most surprising discovery, predominantly of agar-agar immobilized xylanase, which held 31% activity after 7 cycles. These outcomes prove the biotechnical and monetary advantages of immobilization which help in an assortment of industrial applications.

Get Rid of the Shackle from Supports: Construct Recoverable Semi-Homogeneous Catalysts with Attapulgite

Traditionally, the immobilized catalyst sacrifices a part of catalytic activity for its recyclability. To reproduce the catalytic activity of active specie, we construct a novel strategy called "adsorption-desorption-adsorption". Since the...

Application of Immobilized Cholest-4-en-3-one Δ1-Dehydrogenase from Sterolibacterium Denitrificans for Dehydrogenation of Steroids

Cholest-4-en-3-one Δ1-dehydrogenase (AcmB) from Sterolibacterium denitrificans was successfully immobilized on 3-aminopropyltrimethoysilane functionalized mesoporous cellular foam (MCF) and Santa Barbara Amorphous (SBA-15) silica supports using adsorption or covalently with glutaraldehyde or divinyl sulfone linkers. The best catalyst, AcmB on MCF linked covalently with glutaraldehyde, retained the specific activity of the homogenous enzyme while exhibiting a substantial increase of the operational stability. The immobilized enzyme was used continuously in the fed-batch reactor for 27 days, catalyzing 1,2-dehydrogenation of androst-4-en-3-one to androst-1,4-dien-3-one with a final yield of 29.9 mM (8.56 g/L) and 99% conversion. The possibility of reuse of the immobilized catalyst was also demonstrated and resulted in a doubling of the product amount compared to that in the reference homogenous reactor. Finally, it was shown that molecular oxygen from the air can efficiently be used as an electron acceptor either reoxidizing directly the enzyme or the reduced 2,4-dichlorophenolindophenol (DCPIPH2).

Application of Immobilized Cholest-4-en-3-one Δ1-Dehydrogenase from Sterolibacterium denitrificans for Dehydrogenation of Steroids

Cholest-4-en-3-one Δ1-dehydrogenase (AcmB) from Sterolibacterium denitrificans is successfully immobilized on 3-aminopropyltrimethoysilane functionalized MCF and SBA-15 silica supports using adsorption or covalently with glutaraldehyde or divinyl sulfone linkers. The best catalyst, AcmB on MCF linked covalently with glutaraldehyde, retains the specific activity of the homogenous enzyme while exhibiting a substantial increase of the operational stability. The immobilized enzyme was used continuously in the fed-batch reactor for 27 days, catalyzing 1,2-dehydrogenation of androst-4-en-3-one to androst-1,4-dien-3-one with a final yield of 29.9 mM (8.56 g/L) and 99% conversion. The possibility of reuse of the immobilized catalyst was also demonstrated and resulted with a doubling of the product amount compared to that in the reference homogenous reactor. Finally, it was shown that molecular oxygen from the air can efficiently be used as an electron acceptor either reoxidizing directly the enzyme or the reduced DCPIPH2. Keywords: 3-ketosteroid D1-dehydrogenase; KSTD; KSDH; AcmB; 1,2-dehydrogenation; cholest-4-en-3-one Δ1-dehydrogenase; enzyme immobilization, FAD-dependent enzymes; enzyme immobilization;

Mesoporous Silica-Supported Ionic Liquids as Catalysts for Styrene Carbonate Synthesis from CO2

Various types of mesoporous silica were used as carriers to synthesize a series of immobilized imidazolium-based ionic liquids. Their activity was tested in the synthesis of styrene carbonate from CO2 and styrene. This is one-pot process, whereby two stages are carried out in one reactor and there is no need to isolate the intermediate product, epoxide. A systematic study on the influence of parameters such as temperature, the reaction time, CO2 pressure, as well as the amount and type of catalyst used was carried out. A strong synergistic catalytic effect of ionic liquid and Lewis acid was observed in promoting this reaction. The addition sequence of regents and amount of immobilized catalyst were considered crucial for the synthesis of styrene carbonate from CO2 and styrene. The tested silica-supported ionic liquids gave an easily-recyclable system which under the most favorable conditions ([mtespim]Cl/@SiO2; ZnBr2, 0.1 mol%; 110 °C, 4 h, 1 MPa) can be reused without a significant loss of catalytic activity nor selectivity.