Development of nanosized catalysts for processing synthesis gas to methanol

Conversion of carbon dioxide into chemical waste-free feedstock (carbonates, cyclocarbonates, synthesis gas) requires the use of a two-stage reaction (conversion of carbon monoxide under pressure, followed by purification of the converted gas from carbon dioxide with hot potash or monoethanolamine and removal of residual carbon oxides by catalytic hydrogenation) of the reaction. The main problem with this transformation is that, for energetic reasons, these reactions are difficult to coordinate with each other. To ensure the compatibility of the processes from a thermodynamic point of view, appropriate nanocatalysts are needed to obtain a useful product in the course of the reactions. The authors carried out field tests of various catalysts, discovered the compatibility of the reaction with two catalysts with the required properties: a copper compound for the first stage of the reaction and a compound of zinc oxide for the second stage, and also demonstrated the feasibility of this reaction using phenylethylene contained in a hydrocarbon compound. The numerous processes that can be used to produce methanol can be divided into three categories: indirect, direct, and biofuel. Indirect conversion is widespread throughout the world. This conversion takes place in a process in which biomass, coal or natural gas is converted to a mixture of hydrogen and carbon monoxide known as synthesis gas. The syngas is converted to methanol using a variety of conversion methods. Research on the development and improvement of nanocatalysts for the chemical processing of carbon dioxide into methanol has been carried out. An algorithm has been developed for modeling the composition, structure, and properties of nanocatalysts, and a number of new compounds have been synthesized that are capable of retaining cations with different oxidation states and sizes in the crystal lattice. Work has been carried out to improve nanocatalysts based on nickel for deep methanol hydrotreating.

Optimization of Esterification Reaction Conditions Through the Analysis of the Main Significant Variables

Biodiesel production from residual sources is gaining considerable attention nowadays. Consequently, many different studies with in-depth analysis concerning the influence of the transesterification reaction conditions are available in the literature. However, further evaluation of the esterification of fatty acids in the biodiesel industry is still needed. In this study, different parameters influencing the esterification reaction behavior using ethanol as the alcohol and lauric acid as the FFA are analyzed through factorial design and ANOVA methodologies to verify which ones are significant in the reaction. In total, four parameters were evaluated: temperature, catalyst concentration, ethanol/FFA ratio, and ethanol/water ratio. The temperature and ethanol/water ratio had a major influence on the reaction, as increasing these parameters greatly improved reaction conversion. It was also verified that using hydrous ethanol in the esterification reaction is possible in some conditions.

Lattice Boltzmann method investigation of a reactive electro-kinetic flow in porous media: towards a phenomenological model

A model based on the Lattice Boltzmann method is developed to study the flow of reactive electro-kinetic fluids in porous media. The momentum, concentration and electric/potential fields are simulated via the Navier–Stokes, advection–diffusion/Nernst–Planck and Poisson equations, respectively. With this model, the total density and velocity fields, the concentration of reactants and reaction products, including neutral and ionized species, the electric potential and the interaction forces between the fields can be studied, and thus we provide an insight into the interplay between chemistry, flow and the geometry of the porous medium. The results show that the conversion efficiency of the reaction can be strongly influenced by the fluid velocity, reactant concentration and by porosity of the porous medium. The fluid velocity determines how long the reactants stay in the reaction areas, the reactant concentration controls the amount of the reaction material and with different dielectric constant, the porous medium can distort the electric field differently. All these factors make the reaction conversion efficiency display a non-trivial and non-monotonic behaviour as a function of the flow and reaction parameters. To better illustrate the dependence of the reaction conversion efficiency on the control parameters, based on the input from a number of numerical investigations, we developed a phenomenological model of the reactor. This model is capable of capturing the main features of the causal relationship between the performance of the reactor and the main test parameters. Using this model, one could optimize the choice of reaction and flow parameters in order to improve the performance of the reactor and achieve higher production rates. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

Chiral Synthesis of 3-Amino-1-phenylbutane by a Multi-Enzymatic Cascade System

Asymmetric synthesis of chiral amines from prochiral ketones using transaminases is an attractive biocatalytic strategy. Nevertheless, it is hampered by its unfavorable thermodynamic equilibrium. In the present work, an insitu by-product removal strategy was applied for the synthesis of 3-amino-1-phenylbutane (3-APB) by coupling a transaminase with a pyruvate decarboxylase (PDC), which does not require the use of any expensive additional cofactor. Using this strategy, the pyruvate obtained in the transamination reaction is transformed by PDC into acetaldehyde and CO2 which are of high volatility. Two different transaminases from Chromobacterium violaceum (CviTA) and Vibrio fluvialis (VflTA) were characterized to find out the appropriate pH conditions. In both cases, the addition of PDC dramatically enhanced 3-APB synthesis. Afterwards, different reaction conditions were tested to improve reaction conversion and yield. It was concluded that 30 °C and a 20-fold alanine excess lead to the best process metrics. Under the mentioned conditions, yields higher than 60% were reached with nearly 90% selectivity using both CviTA and VflTA. Moreover, high stereoselectivity for (S)-3-APB was obtained and ee of around 90% was achieved in both cases. For the first time, the asymmetric synthesis of 3-APB using PDC as by-product removal system using CviTA is reported.

Optimizing the Sodium Hydroxide Conversion Using Regression Analysis in CSTR

The current study deals with the maximization of NaOH conversion using step-wise regression analysis in a CSTR. The dependence of temperature, volume, agitation rate, and feed rate on reactor performance is examined as well as interaction outcome of the operating parameters. The concentration of the reactants was fixed at 0.1 M. The steady state conversion with respect to NaOH is analyzed to find the process performance. Step-wise regression analysis is used to remove an insignificant factors. The agitation rate (X2) and feed rate (X3) proved to have an insignificant influence on the reaction conversion at a significant level (α) of 5%. Consequently, the temperature (X1) and reaction volume (X4) were found to have significant effect on the reaction conversion using step-wise regression. The temperature and volume dependence on steady state NaOH conversion were described by a polynomial model of 2nd and 3rd order. A maximal steady state conversion equal to 63.15% was obtained. No improvement was found in reaction conversion with 3rd order polynomial, so the second order polynomial is considered as the optimum reaction conversion modal. It may be recommended that 2nd order regression polynomial model adequately represents the experimental data very well.

Pengaruh Kadar Suspensi Pati Kulit Pisang Kepok pada Kinetika Reaksi Proses Hidrolisis

Banana peel is one of the wastes that can pollute the environment so it needs to be utilized. One of the ingredients in kepok banana peels is starch (carbohydrates). Banana peel starch can be converted into glucose by hydrolysis method. This study aimed to find out the effect of banana peel starch suspension levels on the reaction kinetics of the hydrolysis process. The hydrolysis process used 2 N oxalic acid with reaction times of 10, 20, 30, 40 and 50 minutes and the levels of suspension of kepok banana peel starch (gr/mlcamp) were 10/250, 20/250 and 30/250. The results showed that the optimum results were obtained at a suspension content of 10/250 gr/ml with a reaction conversion reaching 35% at a time of 50 minutes at a constant temperature of 100°C. Keywords : Hydrolysis, Banana Kepok, Reaction Kinetics

Applicability of Membrane Reactor For Producing Environment Friendly Fuel Additive Glycerol Carbonate

<p>Production of glycerol carbonate (GLC) that is a fuel additive from green solvent dimethyl carbonate (DMC) and biodiesel by-product glycerin is environmentally friendly synthesis. The usage of waste glycerol from biodiesel plant makes the production cost lower. When the membrane aided technique is used for the production of GLC, this technique will be very promising technique. Because membrane applications are environment and energy friendly economical applications. The production with membrane aided can be made by catalytic membrane. In this study, catalytic membranes were developed from synthetic and natural materials to produce GLC by transesterification reaction between glycerol and DMC. The reaction gives methanol as byproduct. The catalytic membranes were used methanol retentive material for increasing the reaction conversion of glycerol to glycerol carbonate. The synthetic catalytic membrane materials were poly(vinylalcohol)(PVA), poly(vinylpyrrolidone) (PVP), Poly(4-vinylpyridine) (P4VP) polymers and CaO. The natural catalytic membrane material was chitosan biopolymer and waste eggshell. The properties of by-product methanol retentive of the polymeric membranes were determined from sorption tests. The tests were shown that the catalytic membranes would sorp by-product methanol during reaction. This pointed out that GLC synthesis can be made by membrane aided technique such as membrane reactor.</p>

Using TOF-SIMS Spectrometry to Study the Kinetics of the Interfacial Retro Diels–Alder Reaction

In this work, the use of Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) was explored as a technique for monitoring the interfacial retro Diels–Alder (retro DA) reaction occurring on well-controlled self-assembled monolayers (SAMs). A molecule containing a Diels–Alder (DA) adduct was grafted on to the monolayers, then the surface was heated at different temperatures to follow the reaction conversion. A TOF-SIMS analysis of the surface allowed the detection of a fragment from the molecule, which is released from the surface when retro DA reaction occurs. Hence, by monitoring the decay of this fragment’s peak integral, the reaction conversion could be determined in function of the time and for different temperatures. The viability of this method was then discussed in comparison with the results obtained by 1H NMR spectroscopy.

Biocatalytic Reduction of Formaldehyde to Methanol: Effect of pH on Enzyme Immobilization and Reactive Membrane Performance

Thermodynamic stabled CO2 molecules can be biocatalytically reduced to methanol via three cascade dehydrogenases (formate, formaldehyde and alcohol) with the aid of cofactor as the electron donor. In this study, Alcohol dehydrogenase (EC 1.1.1.1), the third step of the cascade enzymatic reaction which catalyzed formaldehyde (CHOH) to methanol (CH3OH) will be immobilized in an ultrafiltration membrane. The enzyme will be immobilized in the support layer of a poly(ether)sulfone (PES) membrane via a technique called fouling induced enzyme immobilization. The objective of this study is to evaluate the effect of varying pH (acid (pH 5), neutral (pH 7) and alkaline (pH 9)) of the feed solution during immobilization process of ADH in the membrane in terms of permeate flux, observed rejection, enzyme loading and fouling mechanism. The experiment was conducted in a pressure driven, dead-end stirred filtration cell. Reaction conversion and biocatalytic productivity will be also evaluated. The results showed that permeate flux for acid solution were the lowest during immobilization. High concentration polarization and fouling resistance cause lower observed rejection for pH 7 and 9. Enzyme loading for pH 5 give 73.8% loading rate which is the highest compared to 62.4% at pH 7 and 70.1% at pH 9. Meanwhile, the conversion rate during the reaction shows that reaction on fouled membrane showed more than 90% conversion for pH 5 and 7. The fouling model predicted that irreversible fouling occurs during enzyme immobilization at pH 7 with standard blocking mechanism while reversible fouling occurs at pH 5 and 9 with intermediate and complete blocking, respectively. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).