scholarly journals Modernization of the Catalyst Composition for the Synthesis of Acrylic Acid Nitrile in Aqueous and Non-Aqueous Media

2021 ◽  
Vol 01 (09) ◽  
Author(s):  
Yangibaev S. ◽  
◽  
◽  
Keyword(s):  
Liquid Phase ◽  
Acrylic Acid ◽  
High Activity ◽  
Aqueous Media ◽  
Catalyst Composition ◽  
Water Based ◽  
Acid Nitrile ◽  
Positive Effect

The effect of the components of the catalyst solution for the hydrocyanation of acetylene on the activity and selectivity of the process under liquid-phase conditions has been studied. The introduction of ZnSO 4 and ZnO additives into the shop catalyst did not give a positive effect under these conditions. Studies of catalysts in non-aqueous media lead to an increase in their activity and selectivity in comparison with aqueous media. It has been shown that the composition of the CuCl - NMP - DMF catalyst is characterized by high activity (up to 32 g / l.h.) and selectivity (83-90%), i.e. the activity of this composition is almost twice as high as compared to the water-based ones (12-18 g l.h.).

Cyclohexylation of Naphthalene Over USY Zeolites

1999 ◽  
Vol 64 (1) ◽  
pp. 138-148 ◽  
Author(s):  
Miroslav Michvocík ◽  
Dušan Mravec ◽  
Milan Hronec ◽  
Agáta Smiešková ◽  
Pavol Hudec
Keyword(s):  
Liquid Phase ◽  
Hydrochloric Acid ◽  
Thermal Stabilization ◽  
Y Zeolite ◽  
Zeolite Structure ◽  
Positive Effect

The influence of thermal stabilization of NH4-Y zeolite and modification of USY zeolites with solutions of hydrochloric acid on the cyclohexylation of naphthalene in the liquid phase was studied. Removal of the part of extra-framework aluminium from zeolite structure has a positive effect on both conversion of naphthalene and amount of dicyclohexylnaphthalenes formed. Modification of zeolites leads to an increase in conversion and selectivity of β-substitution in the naphthalene cyclohexylation.

scholarly journals Liquid–Liquid Phase Separation Enhances TDP-43 LCD Aggregation but Delays Seeded Aggregation

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548
Author(s):  
Donya Pakravan ◽  
Emiel Michiels ◽  
Anna Bratek-Skicki ◽  
Mathias De Decker ◽  
Joris Van Lindt ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Hydrophobic Interactions ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
End Stage ◽  
Positive Effect ◽  
Self Aggregation ◽  
Lateral Sclerosis ◽  
Liquid Liquid Phase Separation

Aggregates of TAR DNA-binding protein (TDP-43) are a hallmark of several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Although TDP-43 aggregates are an undisputed pathological species at the end stage of these diseases, the molecular changes underlying the initiation of aggregation are not fully understood. The aim of this study was to investigate how phase separation affects self-aggregation and aggregation seeded by pre-formed aggregates of either the low-complexity domain (LCD) or its short aggregation-promoting regions (APRs). By systematically varying the physicochemical conditions, we observed that liquid–liquid phase separation (LLPS) promotes spontaneous aggregation. However, we noticed less efficient seeded aggregation in phase separating conditions. By analyzing a broad range of conditions using the Hofmeister series of buffers, we confirmed that stabilizing hydrophobic interactions prevail over destabilizing electrostatic forces. RNA affected the cooperativity between LLPS and aggregation in a “reentrant” fashion, having the strongest positive effect at intermediate concentrations. Altogether, we conclude that conditions which favor LLPS enhance the subsequent aggregation of the TDP-43 LCD with complex dependence, but also negatively affect seeding kinetics.

Preparation of Core-Shell Silica - 12-Tungstophosphoricacid Nanoparticles for Acylation of Aromatics

2013 ◽  
Vol 706-708 ◽  
pp. 219-223
Author(s):  
Hsiu Ling Hsu ◽  
Rosilda Selvin ◽  
L. Selva Roselin
Keyword(s):  
Liquid Phase ◽  
High Activity ◽  
Solid Acid ◽  
Coke Formation ◽  
Solid Acid Catalysts ◽  
Core Shell ◽  
Acid Catalysts ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles ◽  
Enhanced Selectivity

A variety of solid acid catalysts especially 12-Tungstophosphoricacid (DTP) supported on silica has been reported for the acylation of anisole, veratrole and toluene. However, the activity of this catalyst is susceptible to coke formation or poor activity. This paper reports the novelties of steam treated SiO2-DTP core-shell nanoparticles, which exhibits tremendous stability, high activity and enhanced selectivity in the liquid-phase acylation of anisole, veratrole and toluene as compared to conventional DTP supported on silica.

scholarly journals Aplicação de óxidos mistos de molibdênio, vanádio, tungstênio e cobre como catalisadores na produção do ácido acrílico

2020 ◽  
Author(s):  
◽  
W. M. Fantim
Keyword(s):  
Block Copolymer ◽  
Acrylic Acid ◽  
Hydrothermal Treatment ◽  
Crystalline Phase ◽  
Heterogeneous Catalysts ◽  
Raw Material ◽  
Oxide Content ◽  
Propene Oxidation ◽  
Synthesis Conditions ◽  
Catalyst Composition

Acrylic acid is a product with several applications in the chemical industry, the main one is the production of sodium polyacrylate, a superabsorbent material used in the toiletries manufacture. Currently acrylic acid is obtained from propene oxidation using heterogeneous Mo/Bi and Mo/V oxide-based catalysts. In this process, propene is first oxidized to acrolein, which is then oxidized to acrylic acid. Although this is already a consolidated process, propylene comes from petrochemical sources and thus there is a concern to search for alternative routes to the use of this raw material and one of the possibilities is to synthesize acrolein from glycerol dehydration using specific catalysts. For the project, heterogeneous catalysts were prepared to obtain the acrylic acid, first evaluated in the oxidation of acrolein and later in the glycerol oxideshydration. Three types of samples were synthesized with different compositions B1- Mo12V4,8W2,4Cu2,2Si8,4; B2-Mo12V2W0,5Si6,2 and B3-Mo12V2,7Si6,2) by four preparation methods, namely by evaporation, evaporation followed by hydrothermal treatment, hydrothermal treatment (TH) and using a block copolymer. For the last two methods a more detailed study was performed to determine the best synthesis conditions (Phase I), and it was found that the total dissolution of the reagents in the mixture before TH resulted in samples with higher crystallinity and less active phase loss in the liquid and the use of a cold dissolved block copolymer contributed to an increase in pore volume. In the second stage, the materials synthesized by the four proposed methods were characterized and evaluated in reactor in acrylic acid production. The samples B1 showed different crystalline phase formation depending on the preparation method used, and in samples B2 and B3 the main phase was identified as a-MoO3, regardless of the method used. The samples synthesized by evaporation followed by TH showed the highest selectivity for acrylic acid formation from acrolein for the same catalyst composition, which may be related to the higher vanadium oxide content present in samples identified by FRX and the formation of the crystalline phase V0.35Mo4,65O14. The best performance was observed in sample B1-EV+TH with selectivity of 50.59% and 3.61% for acrylic acid in the processes from acrolein and glycerol, respectively

scholarly journals Synthesis of amphiphilic copolymers based on acrylic acid, fluoroalkyl acrylates and n-butyl acrylate in organic, aqueous–organic, and aqueous media via RAFT polymerization

RSC Advances ◽  
2017 ◽  
Vol 7 (39) ◽  
pp. 24522-24536 ◽  
Author(s):  
N. S. Serkhacheva ◽  
O. I. Smirnov ◽  
A. V. Tolkachev ◽  
N. I. Prokopov ◽  
A. V. Plutalova ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Polyacrylic Acid ◽  
Self Assembly ◽  
Butyl Acrylate ◽  
Raft Polymerization ◽  
Aqueous Media ◽  
Amphiphilic Copolymers

Hydrophilic and amphiphilic polymeric trithiocarbonates based on polyacrylic acid are able to provide polymerization-induced self-assembly in copolymerization of butyl and fluoroalkyl acrylates.

Dispersion Polymerization of Acrylamide and Acrylic Acid in Aqueous Media

2009 ◽  
Vol 87-88 ◽  
pp. 233-238
Author(s):  
Jiao Lu ◽  
Bo Peng ◽  
Ming Yuan Li ◽  
Mei Qin Lin
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Acrylic Acid ◽  
Intrinsic Viscosity ◽  
Salt Concentration ◽  
Apparent Viscosity ◽  
Dispersion Polymerization ◽  
Aqueous Media ◽  
Salt Solutions ◽  
Aqueous Salt Solutions

Dispersion polymerization of acrylamide and acrylic acid was successfully carried out in aqueous salt solutions using anionic polyelectrolytes as stabilizers. The influences of aqueous solution of salt concentration, molecular weight and concentration of the stabilizers on the apparent viscosity and stability of the dispersions, and on the molecular weight of the polymers prepared were investigated. The results showed that stable dispersions could be obtained on condition that salt concentration was between 26%~30%, concentration of stabilizers between 8%~12%, and intrinsic viscosity of stabilizers between 2.977~3.740 dL/g. With salt concentration ranging from 26% to 30%, molecular weight of products increased first and then decreased. Molecular weight of products was hardly changed when concentration of stabilizer was between 8%~12%. When intrinsic viscosity of stabilizer was between 2.977~3.740 dL/g, increase of the molecular weight of stabilizer resulted in a decrease in the molecular weight of the products.

Preparation and Electrical Properties of Multilayer Zinc Oxide Varistor by Gelcasting

2014 ◽  
Vol 852 ◽  
pp. 285-290
Author(s):  
Mao Yan Fan ◽  
Li Fang Zhang ◽  
Hong Xiao ◽  
Tian Tian Xie
Keyword(s):  
Electrical Properties ◽  
Tape Casting ◽  
Optimum Concentration ◽  
Water Soluble ◽  
Solid Loading ◽  
High Solid Loading ◽  
Water Based ◽  
Zno Varistors ◽  
Zinc Oxide Varistor ◽  
Positive Effect

Multilayer ZnO varistors were prepared by aqueous gel tape casting with water-soluble acrylamide as binder. 0.8wt% PAA dispersant was found to be the optimum concentration needed to prepare stable slurry. Plasticizer glycerol has a positive effect on the fluidity of the suspension and oxygen anti-polymerizing inhibitor PEG 2000 deteriorated the fluidity. The addition of 15wt. % PEG2000 eliminates the surface exfoliation absolutely due to the oxygenation of ether units. The solid loading of the slurry was about 71wt% compared to the custom acrylic formulation binder 60wt%. The multilayer ZnO varistors prepared by aqueous gel tape casting display comparable good electrical properties to those prepared by water-based tape casting using custom acrylic formulation binder which is attributed to the high solid loading of slurry.

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