scholarly journals Synthesis and Application of Heterogeneous Catalysts Based on Heteropolyacids for 5-Hydroxymethylfurfural Production from Glucose

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 655 ◽  
Author(s):  
Jéssica Siqueira Mancilha Nogueira ◽  
João Paulo Alves Silva ◽  
Solange I. Mussatto ◽  
Livia Melo Carneiro
Keyword(s):  
Experimental Design ◽  
Heterogeneous Catalysts ◽  
Catalyst Concentration ◽  
Active Phase ◽  
Production Performance ◽  
Reaction Conditions ◽  
Catalyst Synthesis ◽  
Synthesis Conditions ◽  
Different Temperatures ◽  
Water Ratio

This study aimed to evaluate the synthesis and application of heterogeneous catalysts based on heteropolyacids for 5-hydroxymethylfurfural (HMF) production from glucose. Initially, assays were carried out in order to establish the most favorable catalyst synthesis conditions. For such purpose, calcination temperature (300 or 500 °C), type of support (Nb2O5 or Al2O3), and active phase (H3PW12O40—HPW or H3PMo12O40—HPMo) were tested and combined based on Taguchi’s L8 orthogonal array. As a result, HPW-Nb2O5 calcined at 300 °C was selected as it presented optimal HMF production performance (9.5% yield). Subsequently, the reaction conditions capable of maximizing HMF production from glucose using the selected catalyst were established. In these experiments, different temperatures (160 or 200 °C), acetone-to-water ratios (1:1 or 3:1 v/v), glucose concentrations (50 or 100 g/L), and catalyst concentrations (1 or 5% w/v) were evaluated according to a Taguchi’s L16 experimental design. The conditions that resulted in the highest HMF yield (40.8%) consisted of using 50 g/L of glucose at 160 °C, 1:1 (v/v) acetone-to-water ratio, and catalyst concentration of 5% (w/v). Recycling tests revealed that the catalyst can be used in four runs, which results in the same HMF yield (approx. 40%).

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

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Bruna Ricetti Margarida ◽  
Luana I. Flores ◽  
Luiz Fernando De Lima Luz Jr. ◽  
Marcelo Kaminski Lenzi
Keyword(s):  
Catalyst Concentration ◽  
Biodiesel Production ◽  
Major Influence ◽  
Esterification Reaction ◽  
Reaction Conditions ◽  
Reaction Behavior ◽  
Reaction Conversion ◽  
Depth Analysis ◽  
Hydrous Ethanol ◽  
Water Ratio

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.

scholarly journals Production of 5-Hydroxymethylfurfural from Direct Conversion of Cellulose Using Heteropolyacid/Nb2O5 as Catalyst

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1417
Author(s):  
Jéssica Siqueira Mancilha Nogueira ◽  
Vinícius Tomaz Santana ◽  
Paulo Vitor Henrique ◽  
Leandro Gonçalves de Aguiar ◽  
João Paulo Alves Silva ◽  
...  
Keyword(s):  
Experimental Data ◽  
Experimental Design ◽  
Kinetic Study ◽  
Catalyst Concentration ◽  
Direct Conversion ◽  
Central Composite Rotatable Design ◽  
Reaction Conditions ◽  
Optimized Conditions ◽  
Different Sources ◽  
Central Composite

This study aimed to select the best reaction conditions to produce 5-hydroxymethylfurfural (HMF) from cellulose using heterogeneous catalyst based on a heteropolyacid (H3PW12O40—HPW) and Nb2O5. Initially, the influence of the temperature (160 or 200 °C), acetone:water ratio (50:50 or 75:25 v/v), cellulose load (5% or 10% w/v) and catalyst concentration (1% or 5% w/v) on HMF production from cellulose was evaluated through a Taguchi’s L16 screening experimental design. Afterwards, the main variables affecting this process, namely the temperature (160–240 °C) and acetone:water ratio (60:40–90:10 v/v), were optimized using a central composite rotatable design. Next, a kinetic study on HMF production from cellulose was carried out. Finally, HMF production from cellulose obtained from different biomass sources was evaluated. It was found that the reaction conditions able to result in maximum HMF yield, i.e., around 20%, were 200 °C, acetone:water ratio of 75:25 (v/v), 10% w/v of cellulose, and 5% w/v of catalyst concentration. The kinetic study revealed that the Langmuir–Hinshelwood–Hougen–Watson approach fit to the experimental data. Under the optimized conditions, the catalyst HPW/Nb2O5 was also effective in converting different sources of cellulose into HMF.

scholarly journals Carbonization and Regeneration of Mo/ZSM-5 Catalysts for Methane Dehydroaromatization

2017 ◽  
Vol 7 (2) ◽  
pp. 115 ◽  
Author(s):  
Z.R. Ismagilov ◽  
L.T. Tsikoza ◽  
E.V. Matus ◽  
G.S. Litvak ◽  
I.Z. Ismagilov ◽  
...  
Keyword(s):  
Methane Concentration ◽  
Stable Operation ◽  
Reaction Conditions ◽  
Catalyst Synthesis ◽  
Synthesis Conditions ◽  
Carbonaceous Deposits ◽  
Oxidative Treatment ◽  
Treatment Conditions ◽  
Methane Dehydroaromatization ◽  
Mo Content

<p>The character of carbonaceous deposits formed during methane dehydroaromatization reaction in the presence of Mo/ZSM-5 catalysts was studied by differential thermal analysis. The dependence of the concentration and condensation degree (C/H ratio) of the carbonaceous deposits on the catalyst synthesis conditions (Mo content = 1-10%, Si/Al ratio in the initial H-ZSM-5 = 17-45) and reaction conditions (feed flow rate = 405-1620 h<sup>-1</sup>, methane concentration = 90-98%, reaction temperature = 720-780 °C) was investigated. The oxidative treatment conditions of carbonized Mo/ZSM-5 catalysts providing stable operation of the catalysts under multiple reaction-oxidative treatment cycles were selected.</p>

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Catalysts for hydrogenation of CO2 into components of motor fuels

2020 ◽  
pp. 1-18
Author(s):  
Yu.V. Bilokopytov ◽  
◽  
S.L. Melnykova ◽  
N.Yu. Khimach ◽  
◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Heterogeneous Catalysts ◽  
Fossil Fuels ◽  
Catalyst Stability ◽  
Co2 Conversion ◽  
Active Components ◽  
Synthesis Conditions ◽  
Hydrogenation Of Co2 ◽  
Mesoporous Zeolites ◽  
Motor Fuels

CO2 is a harmful greenhouse gas, a product of chemical emissions, the combustion of fossil fuels and car exhausts, and it is a widely available source of carbon. The review considers various ways of hydrogenation of carbon dioxide into components of motor fuels - methanol, dimethyl ether, ethanol, hydrocarbons - in the presence of heterogeneous catalysts. At each route of conversion of CO2 (into oxygenates or hydrocarbons) the first stage is the formation of CO by the reverse water gas shift (rWGS) reaction, which must be taken into account when catalysts of process are choosing. The influence of chemical nature, specific surface area, particle size and interaction between catalyst components, as well as the method of its production on the CO2 conversion processes is analyzed. It is noted that the main active components of CO2 conversion into methanol are copper atoms and ions which interact with the oxide components of the catalyst. There is a positive effect of other metals oxides additives with strong basic centers on the surface on the activity of the traditional copper-zinc-aluminum oxide catalyst for the synthesis of methanol from the synthesis gas. The most active catalysts for the synthesis of DME from CO2 and H2 are bifunctional. These catalysts contain both a methanol synthesis catalyst and a dehydrating component, such as mesoporous zeolites with acid centers of weak and medium strength, evenly distributed on the surface. The synthesis of gasoline hydrocarbons (≥ C5) is carried out through the formation of CO or CH3OH and DME as intermediates on multifunctional catalysts, which also contain zeolites. Hydrogenation of CO2 into ethanol can be considered as an alternative to the synthesis of ethanol through the hydration of ethylene. High activation energy of carbon dioxide, harsh synthesis conditions as well as high selectivity for hydrocarbons, in particular methane remains the main problems. Further increase of selectivity and efficiency of carbon dioxide hydrogenation processes involves the use of nanocatalysts taking into account the mechanism of CO2 conversion reactions, development of methods for removing excess water as a by-product from the reaction zone and increasing catalyst stability over time.

scholarly journals Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1680
Author(s):  
Marta A. Andrade ◽  
Luísa M. D. R. S. Martins
Keyword(s):  
Heterogeneous Catalysts ◽  
Carbon Materials ◽  
Oxygen Species ◽  
Styrene Oxidation ◽  
Reaction Conditions ◽  
Reactive Metal ◽  
Catalytic Systems ◽  
Tert Butyl Hydroperoxide ◽  
Metal Organic ◽  
Important Intermediate

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.

scholarly journals An Overview of Biodiesel Production via Calcium Oxide Based Catalysts: Current State and Perspective

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3950
Author(s):  
Hoora Mazaheri ◽  
Hwai Chyuan Ong ◽  
Zeynab Amini ◽  
Haji Hassan Masjuki ◽  
M. Mofijur ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Calcium Oxide ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Biodiesel Production ◽  
Catalyst Synthesis ◽  
Process Improvements ◽  
Current State ◽  
The Common ◽  
Activity Mechanism

Biodiesel is a clean, renewable, liquid fuel that can be used in existing diesel engines without modification as pure or blend. Transesterification (the primary process for biodiesel generation) via heterogeneous catalysis using low-cost waste feedstocks for catalyst synthesis improves the economics of biodiesel production. Heterogeneous catalysts are preferred for the industrial generation of biodiesel due to their robustness and low costs due to the easy separation and relatively higher reusability. Calcium oxides found in abundance in nature, e.g., in seashells and eggshells, are promising candidates for the synthesis of heterogeneous catalysts. However, process improvements are required to design productive calcium oxide-based catalysts at an industrial scale. The current work presents an overview of the biodiesel production advancements using calcium oxide-based catalysts (e.g., pure, supported, and mixed with metal oxides). The review discusses different factors involved in the synthesis of calcium oxide-based catalysts, and the effect of reaction parameters on the biodiesel yield of calcium oxide-based catalysis are studied. Further, the common reactor designs used for the heterogeneous catalysis using calcium oxide-based catalysts are explained. Moreover, the catalytic activity mechanism, challenges and prospects of the application of calcium oxide-based catalysts in biodiesel generation are discussed. The study of calcium oxide-based catalyst should continue to be evaluated for the potential of their application in the commercial sector as they remain the pivotal goal of these studies.

scholarly journals Surface Modification of Fly Ash for Active Catalysis

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Deepti Jain ◽  
Renu Hada ◽  
Ashu Rani
Keyword(s):  
Fly Ash ◽  
Heterogeneous Catalysts ◽  
Chemical Activation ◽  
Alumina Content ◽  
Precipitation Method ◽  
Solid Base ◽  
Thermally Activated ◽  
Flame Atomic Absorption ◽  
Flame Atomic Absorption Spectrophotometer ◽  
Different Temperatures

Fly ash based effective solid base catalyst (KF/Al2O3/fly ash473, KF/Al2O3/fly ash673, and KF/Al2O3/fly ash873) was synthesized by loading KF over chemically and thermally activated fly ash. The chemical activation was done by treating fly ash with aluminum nitrate via precipitation method followed by thermal activation at 650°C to increase the alumina content in fly ash. The increased alumina content was confirmed by SEM-EDX analysis. The alumina enriched fly ash was then loaded with KF (10 wt%) and calcined at three different temperatures 473 K, 673 K and 873 K. The amount of loaded KF was monitored by XRD, FTIR spectroscopy, SEM-EDX, TEM and Flame Atomic Absorption Spectrophotometer. The catalytic activities of the catalysts were tested in the Claisen-Schmidt condensation of benzaldehyde and 4-methoxybenzaldehyde with 2′-hydroxyacetophenone to produce 2′-hydroxychalcone and 4-methoxy-2′-hydroxychalcone respectively. Higher conversion (83%) of benzaldehyde and (89%) of 4-methoxybenzaldehyde reveals that among these heterogeneous catalysts KF/Al2O3/fly ash673 is very active.

Optimization of biodiesel synthesis under simultaneous ultrasound-microwave irradiation using response surface methodology (RSM)

2015 ◽  
Vol 4 (4) ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Teymor Tavakoli Hashjin ◽  
Barat Ghobadian ◽  
Gholamhasan Najafi ◽  
Stefano Mantegna ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Microwave Irradiation ◽  
Response Surface ◽  
Palm Oil ◽  
Catalyst Concentration ◽  
Irradiation Time ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Biodiesel Synthesis

AbstractThis work investigates the effect of simultaneous ultrasound-microwave irradiation on palm oil transesterification and uncovers optimal operating conditions. Response surface methodology (RSM) has been used to analyze the influence of reaction conditions, including methanol/palm oil molar ratio, catalyst concentration, reaction temperature and irradiation time on biodiesel yield. RSM analyses indicate 136 s and 129 s as the optimal sonication and microwave irradiation times, respectively. Optimized parameters for full conversion (97.53%) are 1.09% catalyst concentration and a 7:3.1 methanol/oil molar ratio at 58.4°C. Simultaneous ultrasound-microwave irradiation dramatically accelerates the palm oil transesterification reaction. Pure biodiesel was obtained after only 2.2 min while the conventional method requires about 1 h.

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