scholarly journals Effect of Mo-Doped Mesoporous Al-SSP Catalysts for the Catalytic Dehydration of Ethanol to Ethylene

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Titinan Chanchuey ◽  
Chaowat Autthanit ◽  
Bunjerd Jongsomjit
Keyword(s):  
Catalytic Activity ◽  
Gas Phase ◽  
Sol Gel ◽  
Acid Sites ◽  
Weak Acid ◽  
Acid Property ◽  
Dehydration Reaction ◽  
Ethanol Dehydration ◽  
High Concentration ◽  
Catalytic Activities

The catalytic dehydration of ethanol to ethylene over the mesoporous Al-SSP and Mo-doped Al-SSP catalysts was investigated. The Al-SSP catalyst was first synthesized by the modified sol-gel method and then doped with Mo by impregnation to obtain 1% Mo/Al-SSP and 5% Mo/Al-SSP catalysts (1 and 5 wt% of Mo). The final catalysts were characterized using various techniques such as XRD, N2physisorption, SEM/EDX, TEM, and NH3-TPD. The catalytic activity for all catalysts in gas-phase ethanol dehydration reaction was determined at temperature range of 200°C to 400°C. It was found that the most crucial factor influencing the catalytic activities appears to be the acidity. The acid property of catalysts depended on the amount of Mo loading. Increased Mo loading in Al-SSP resulted in increased weak acid sites, which enhanced the catalytic activity. Besides acidity, the high concentration of Al at surface of catalyst is also essential to obtain high activity. Based on the results, the most suitable catalyst in this study is 1% Mo/Al-SSP catalyst, which can produce ethylene yield of ca. 90% at 300°C with slight amounts of diethyl ether (DEE) and acetaldehyde.

scholarly journals Ethanol Dehydration over WO3/TiO2Catalysts Using Titania Derived from Sol-Gel and Solvothermal Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Anchale Tresatayawed ◽  
Peangpit Glinrun ◽  
Bunjerd Jongsomjit
Keyword(s):  
Physicochemical Properties ◽  
Pore Volume ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Acid Sites ◽  
Ethanol Conversion ◽  
Ethanol Dehydration ◽  
Preparation Methods ◽  
Solvothermal Methods ◽  
Different Characteristics

The present study aims to investigate the catalytic ethanol dehydration to higher value products including ethylene, diethyl ether (DEE), and acetaldehyde. The catalysts used for this reaction were WO3/TiO2catalysts having W loading of 13.5 wt.%. For a comparative study, the TiO2supports employed were varied by two different preparation methods including the sol-gel and solvothermal-derived TiO2supports, denoted as TiO2-SG and TiO2-SV, respectively. It is obvious that the different preparation methods essentially altered the physicochemical properties of TiO2supports. It was found that the TiO2-SV exhibited higher surface area and pore volume and larger amounts of acid sites than those of TiO2-SG. As a consequence, different characteristics of support apparently affected the catalytic properties of WO3/TiO2catalysts. As expected, both catalysts WO3/TiO2-SG and WO3/TiO2-SV exhibited increased ethanol conversion with increasing temperatures from 200 to 400°C. It appeared that the highest ethanol conversion (ca. 88%) at 400°C was achieved by the WO3/TiO2-SV catalysts due to its high acidity. It is worth noting that the presence of WO3onto TiO2-SV yielded a remarkable increase in DEE selectivity (ca. 68%) at 250°C. In summary, WO3/TiO2-SV catalyst is promising to convert ethanol into ethylene and DEE, having the highest ethylene yield of ca. 77% at 400°C and highest DEE yield of ca. 26% at 250°C. These can be attributed to proper pore structure, acidity, and distribution of WO3.

Effect of Rice Husk Ash Based Silicon Dioxide on the Properties of SUZ-4 Zeolite

2017 ◽  
Vol 729 ◽  
pp. 24-29
Author(s):  
Thitipob Sirisoontornpanit ◽  
Atichat Wongkoblab ◽  
Supunnee Junpirom
Keyword(s):  
Silicon Dioxide ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Weak Acid ◽  
Molar Ratio ◽  
Temperature Programmed

SUZ-4 zeolite was synthesized by the sol-gel technique, followed by hydrothermal process. The effect of the molar ratio of rice husk ash based silicon dioxide to silica solution was investigated. The synthesized zeolite was characterized by XRD, SEM, N2 adsorption and temperature programmed desorption. The results show that the SUZ-4 zeolite was formed for all investigated conditions. However, the formation of MER zeolite occurred as an impurity for the content of rice husk ash higher than 75%. A needle shape crystal with mainly microporous structure is the feature of synthesized SUZ-4 zeolite. The result of temperature programmed desorption indicated that the chemical surface property of obtained SUZ-4 zeolite was weak acid sites.

scholarly journals Non-Hydrolytic Sol-Gel Route to a Family of Hybrid Mesoporous Aluminosilicate Ethanol Dehydration Catalysts

2020 ◽  
Author(s):  
Ales Styskalik ◽  
Imène Kordoghli ◽  
Claude Poleunis ◽  
Arnaud Delcorte ◽  
Denis Dochain ◽  
...  
Keyword(s):  
Gas Phase ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Silica Matrix ◽  
Ethanol Dehydration ◽  
One Pot ◽  
Water Contact ◽  
Hybrid Silica ◽  
Mesoporous Aluminosilicate ◽  
Improved Performance

Organic-inorganic hybrid materials are nowadays intensely studied for potential applications in heterogeneous catalysis because their properties and catalytic behavior differ from pristine inorganic counterparts. The organic groups at the catalyst surface can modify not only its hydrophilicity, but also acidity, hydrothermal stability, porosity, etc. In some cases, such properties alteration leads to improved catalytic performance in terms of activity, selectivity, or stability. However, the choice of organic groups stays relatively narrow, as most reports focus on pendant methyl groups. Here, a series of mesoporous hybrid aluminosilicate materials containing various organic groups was prepared in one pot by non-hydrolytic sol-gel (NHSG). Both aromatic and aliphatic, pendant and bridging organic groups were incorporated. The presence of the organic groups in the bulk and at the outermost surface of the materials was verified by solid-state NMR and ToF-SIMS, respectively. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. The organically modified mesoporous aluminosilicate samples were tested as catalysts in the gas phase ethanol dehydration (which relies on solid acids) and most of them outperformed the purely inorganic catalyst benchmark. While a direct influence of surface hydrophilicity or hydrophobicity (as probed by water sorption and water contact angle measurements) appeared unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts can be correlated with a modification of the acidic properties. In turn, acidity is determined by the quality of the dispersion of Al centers in the form of isolated sites in the hybrid silica matrix. All in all, this study establishes a "ranking" for a variety of organic groups in terms of their effect on gas-phase ethanol dehydration to ethylene; ethylene yield decreases in this order: bridging xylylene ≈ pendant methyl > pendant benzyl > bridging methylene ≈ inorganic benchmark (no organic groups) > bridging ethylene.<br>

scholarly journals MCM-41 Supported Co-Based Bimetallic Catalysts for Aqueous Phase Transformation of Glucose to Biochemicals

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 843 ◽  
Author(s):  
Somayeh Taghavi ◽  
Elena Ghedini ◽  
Federica Menegazzo ◽  
Michela Signoretto ◽  
Delia Gazzoli ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Bimetallic Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Mesoporous Structure ◽  
Acid Sites ◽  
Weak Acid ◽  
Reaction Conditions ◽  
Temperature Programmed ◽  
Mcm 41

The transformation of glucose into valuable biochemicals was carried out on different MCM-41-supported metallic and bimetallic (Co, Co-Fe, Co-Mn, Co-Mo) catalysts and under different reaction conditions (150 °C, 3 h; 200 °C, 0.5 h; 250 °C, 0.5 h). All catalysts were characterized using N2 physisorption, Temperature Programmed Reduction (TPR), Raman, X-ray Diffraction (XRD) and Temperature Programmed Desorption (TPD) techniques. According to the N2-physisorption results, a high surface area and mesoporous structure of the support were appropriate for metal dispersion, reactant diffusion and the formation of bioproducts. Reaction conditions, bimetals synergetic effects and the amount and strength of catalyst acid sites were the key factors affecting the catalytic activity and biochemical selectivity. Sever reaction conditions including high temperature and high catalyst acidity led to the formation mainly of solid humins. The NH3-TPD results demonstrated the alteration of acidity in different bimetallic catalysts. The 10Fe10CoSiO2 catalyst (MCM-41 supported 10 wt.%Fe, 10 wt.%Co) possessing weak acid sites displayed the best catalytic activity with the highest carbon balance and desired product selectivity in mild reaction condition. Valuable biochemicals such as fructose, levulinic acid, ethanol and hydroxyacetone were formed over this catalyst.

Synthesis, Characterization and the gas phase catalytic activity of metal doped nanoporous carbon

2002 ◽  
Vol 738 ◽  
Author(s):  
Ponnaiyan Ayyappan ◽  
Henry C. Foley
Keyword(s):  
Catalytic Activity ◽  
Gas Phase ◽  
Nanoporous Carbon ◽  
Acid Base ◽  
Catalytic Activities ◽  
Polyfurfuryl Alcohol ◽  
Evolved Gases ◽  
Acid Base Titration ◽  
Reflectance Ftir ◽  
Metal Doped

ABSTRACTMetal doped nanoporous carbon(NPC) materials, based on polyfurfuryl alcohol and polyethylene glycol were synthesized using new method. The characterization were carried out using acid-base titration, PXRD, TEM, diffused reflectance FTIR, SEM and mass spectrometer. Their gas phase catalytic activities were checked by passing CO and H2 through the catalysts. Carbondioxide and methane were the evolved gases when CO was passed through the catalyst, whereas carbonmonoxide and methane are the resultant gases when H2 was taken up by the catalyst.

scholarly journals Glycerol Hydrogenolysis to 1,2-Propanediol over Novel Cu/ZrO2 Catalysts

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 72
Author(s):  
Giuseppina Luciani ◽  
Giovanna Ruoppolo ◽  
Gianluca Landi ◽  
Valentina Gargiulo ◽  
Michela Alfè ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Copper Deposition ◽  
Biodiesel Production ◽  
Preparation Methods ◽  
Glycerol Hydrogenolysis

Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.

Mildly Acidic Aluminosilicate Catalysts for Stable Performance in Ethanol Dehydration

2020 ◽  
Author(s):  
Ales Styskalik ◽  
Vit Vykoukal ◽  
Luca Fusaro ◽  
Carmela Aprile ◽  
Damien Debecker
Keyword(s):  
Sol Gel ◽  
Coke Formation ◽  
Strong Acid ◽  
Acid Sites ◽  
High Specific Surface Area ◽  
Ethylene Oligomerization ◽  
Zeolite Catalysts ◽  
Activity Levels ◽  
Ethanol Dehydration ◽  
Silica Alumina

Ethanol dehydration is effectively catalyzed by strongly acidic zeolite catalysts which are known, however, to exhibit poor time on stream stability. Alumina and silica-alumina on the other hand are relatively stable but reach only low activity levels. Here, a series of aluminosilicate catalysts (Si:Al ratio = 16) was prepared by non-hydrolytic sol-gel (NHSG) and are shown to feature an intermediate level of activity, between the HZSM-5 zeolite and a commercial silica-alumina. Importantly, the best samples, were very stable with time on stream. Unlike HZSM-5, which also catalyzes ethylene oligomerization due to its strong acid sites and is therefore prone to coking, NHSG prepared catalysts did not produce any traces of ethylene oligomers and did not show any trace of coke formation. Characterization (ICP-OES, N<sub>2</sub> physisorption, TEM, XPS, IR coupled with pyridine adsorption, Raman spectroscopy, solid state NMR spectroscopy) reveal that the unconventional synthetic method presented here allowed to prepare mesoporous aluminosilicate materials with a remarkable degree of homogeneity. It is this thorough dispersion of Al in the amorphous silicate matrix which is responsible for the formation of acid sites which are intermediate (in terms of strength and nature) between those of commercial silica-alumina and HZSM-5 zeolite. The texture of the best NHSG catalyst – mainly mesoporous with a high specific surface area (800 m² g<sup>−1</sup>) and pore volume (0.5 cm³ g<sup>−1</sup>) – was also unaffected after reaction. To overcome deactivation issues in ethanol dehydration, this study suggests to target amorphous aluminosilicate catalysts with open mesoporosity and with an intimate mixing of Al and Si.

scholarly journals Ethanol Dehydration over Hybrid Mesoporous Aluminosilicate Catalysts Obtained in One Pot by Non-Hydrolytic Sol-Gel

2020 ◽  
Author(s):  
Ales Styskalik ◽  
Imène Kordoghli ◽  
Claude Poleunis ◽  
Arnaud Delcorte ◽  
Zdenek Moravec ◽  
...  
Keyword(s):  
Catalyst Activity ◽  
Sol Gel ◽  
Acid Sites ◽  
Silica Matrix ◽  
Methyl Groups ◽  
Ethanol Dehydration ◽  
Alcohol Dehydration ◽  
One Pot ◽  
Surface Hydrophilicity ◽  
Silica Alumina

<p>Ethanol dehydration is effectively catalyzed by solid acids, such as HZSM-5, alumina, or silica-alumina. In these catalysts, the amount, nature, and strength of acid sites is believed to determine catalyst activity and stability. However, surface hydrophilicity or hydrophobicity can be suggested as another decisive catalyst property that can directly influence performance. For example, a more hydrophobic surface might be beneficial in repelling the co-product of the reaction, water. However, these aspects have been studied only scarcely in the context of alcohol dehydration. Here, a series of mesoporous hybrid aluminosilicate catalysts containing CH<sub>3</sub>Si groups was prepared in one pot by non-hydrolytic sol-gel (NHSG). The presence of the methyl groups was verified by IR, solid-state NMR, and ToF-SIMS. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. Two parameters were varied: (i) the Si:Al ratio and (ii) the Si:MeSi ratio. On the one hand, changing the Si:Al ratio had a marked impact on hydrophilicity, as attested by water sorption measurements. On the other hand, unexpectedly, the introduction of methyl groups had no clear influence on sample hydrophilicity. Nevertheless, some of the methylated aluminosilicate catalysts markedly outperformed the purely inorganic catalysts and a commercial silica-alumina benchmark. While a direct influence of surface hydrophilicity or hydrophobicity could be excluded, characterization of acidity (IR-pyridine) revealed that these improved performances are correlated with a modification of the acidic properties in the hybrid catalysts caused by the presence of methyl groups. A decisive role of acidity in ethanol dehydration was confirmed by an experiment with delayed addition of the Al precursor in the NHSG synthesis. This led to a higher Al surface concentration, marked acid sites number increase, and better catalytic performance, even competing with HZSM-5 in terms of activity.</p>

scholarly journals MODIFIED ZSM-5 ZEOLITES IN THE PROCESS OF MONOSACCHARIDE DEHYDRATION

2021 ◽  
pp. 7-17
Author(s):  
Ольга Витальевна Кислица ◽  
Олег Викторович Манаенков ◽  
Екатерина Алексеевна Раткевич ◽  
Валентина Геннадьевна Матвеева
Keyword(s):  
Catalytic Activity ◽  
Tungsten Oxide ◽  
Levulinic Acid ◽  
Catalyst Surface ◽  
Chemical Compounds ◽  
Acid Sites ◽  
Dehydration Reaction ◽  
Noticeable Increase ◽  
Platform Chemical ◽  
Oxide Particles

В данном исследовании была разработана методика синтеза катализаторов на основе цеолитов типа ZSM-5 с различным соотношением Si/Al и количеством кислотных центров, модифицированных оксидом вольфрама (VI). Синтезированные катализаторы были охарактеризованы и протестированы в реакции превращения моносахаридов (фруктозы и глюкозы) в 5-гидроксиметилфурфурол и левулиновую кислоту. Было показано, что введение в состав цеолитов ZSM-5 частиц оксида вольфрама приводит к заметному увеличению количества активных кислотных центров на поверхности катализатора, играющих важную роль в реакции дегидратации моносахаридов. В результате модификации заметно возросла каталитическая активность цеолитов. Результаты исследования показывают перспективность использования цеолитов типа ZSM-5, модифицированных оксидом вольфрама (VI), для конверсии биомассы в платформенные химические соединения. In this study, a method was developed for the synthesis of catalysts based on zeolites of the ZSM-5 type with different Si/Al ratios and the number of acid sites modified with tungsten (VI) oxide. The synthesized catalysts were characterized and tested in the reaction of converting monosaccharides (fructose and glucose) into 5-hydroxymethylfurfural and levulinic acid. It was shown that the introduction of tungsten oxide particles into the composition of ZSM-5 zeolites leads to a noticeable increase in the number of active acid sites on the catalyst surface, which play an important role in the dehydration reaction of monosaccharides. As a result of the modification, the catalytic activity of zeolites has noticeably increased. The results of the study show that the use of zeolites of the ZSM-5 type, modified with tungsten (VI) oxide, is promising for the conversion of biomass into platform chemical compounds.

scholarly journals Ethanol Dehydration over Hybrid Mesoporous Aluminosilicate Catalysts Obtained in One Pot by Non-Hydrolytic Sol-Gel

2020 ◽  
Author(s):  
Ales Styskalik ◽  
Imène Kordoghli ◽  
Claude Poleunis ◽  
Arnaud Delcorte ◽  
Zdenek Moravec ◽  
...  
Keyword(s):  
Catalyst Activity ◽  
Sol Gel ◽  
Acid Sites ◽  
Silica Matrix ◽  
Methyl Groups ◽  
Ethanol Dehydration ◽  
Alcohol Dehydration ◽  
One Pot ◽  
Surface Hydrophilicity ◽  
Silica Alumina

<p>Ethanol dehydration is effectively catalyzed by solid acids, such as HZSM-5, alumina, or silica-alumina. In these catalysts, the amount, nature, and strength of acid sites is believed to determine catalyst activity and stability. However, surface hydrophilicity or hydrophobicity can be suggested as another decisive catalyst property that can directly influence performance. For example, a more hydrophobic surface might be beneficial in repelling the co-product of the reaction, water. However, these aspects have been studied only scarcely in the context of alcohol dehydration. Here, a series of mesoporous hybrid aluminosilicate catalysts containing CH<sub>3</sub>Si groups was prepared in one pot by non-hydrolytic sol-gel (NHSG). The presence of the methyl groups was verified by IR, solid-state NMR, and ToF-SIMS. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. Two parameters were varied: (i) the Si:Al ratio and (ii) the Si:MeSi ratio. On the one hand, changing the Si:Al ratio had a marked impact on hydrophilicity, as attested by water sorption measurements. On the other hand, unexpectedly, the introduction of methyl groups had no clear influence on sample hydrophilicity. Nevertheless, some of the methylated aluminosilicate catalysts markedly outperformed the purely inorganic catalysts and a commercial silica-alumina benchmark. While a direct influence of surface hydrophilicity or hydrophobicity could be excluded, characterization of acidity (IR-pyridine) revealed that these improved performances are correlated with a modification of the acidic properties in the hybrid catalysts caused by the presence of methyl groups. A decisive role of acidity in ethanol dehydration was confirmed by an experiment with delayed addition of the Al precursor in the NHSG synthesis. This led to a higher Al surface concentration, marked acid sites number increase, and better catalytic performance, even competing with HZSM-5 in terms of activity.</p>

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