Molecular Aspects in Porous Silicas Related to Adsorption and Catalytic Processes.

The aim of this special issue is to show the advances in the different applications that inorganic materials based on silica have had in recent years [...

Nb-Based Catalysts for the Valorization of Furfural into Valuable Product through in One-Pot Reaction.

Nb-based catalysts supported on porous silica with different textural properties have been synthesized, characterized, and tested in the one-pot reaction of furfural to obtain valuable chemicals. The catalytic results reveal that the presence of fluoride in the synthesis, which limits the growing of the porous silica, limits diffusional problems of the porous silica, obtaining higher conversion values at shorter reaction times. On the other hand, the incorporation of NbO species in the porous silica provides Lewis acid sites and a small proportion of Brönsted acid sites, in such a way that the main products are alkyl furfuryl ethers, which can be used as fuel additives.

The Role of Copper in the Hydrogenation of Furfural and Levulinic Acid.

Currently, there is a great interest in the development of sustainable and green technologies for production of biofuels and chemicals. In this sense, much attention is being paid to lignocellulosic biomass as feedstock, as alternative to fossil-based resources, inasmuch as its fractions can be transformed into value-added chemicals. Two important platform molecules derived from lignocellulosic sugars are furfural and levulinic acid, which can be transformed into a large spectrum of chemicals, by hydrogenation, oxidation, or condensation, with applications as solvents, agrochemicals, fragrances, pharmaceuticals, among others.

Recent Advances in Mesoporous Materials and Their Biomedical Applications.

Since the beginning of civilization, porous materials have been used for medical purposes [...

Porous SiO Nanospheres Modified with ZrO and Their Use in One-Pot Catalytic Processes to Obtain Value-Added Chemicals from Furfural.

Porous SiO nanospheres were modified with different loadings of ZrO to obtain catalysts with a Si/Zr molar ratio from 2.5 to 30. These materials were characterized by X-ray diffraction, transmission and scanning electron microscopies, N adsorption-desorption at -196 °C, X-ray photoelectron spectroscopy and pyridine and 2-6-dimethylpyridine thermoprogrammed desorption.

Mesoporous Materials: From Synthesis to Applications.

Mesoporous silica are inorganic materials, which are formed by the condensation of sodium silicate or silicon alkoxides around an ordered surfactant used as template [...

Influence of Structure-modifying Agents in the Synthesis of Zr-doped SBA-15 Silica and Their Use as Catalysts in the Furfural Hydrogenation to Obtain High Value-added Products through the Meerwein-Ponndorf-Verley Reduction.

Zr-doped mesoporous silicas with different textural parameters have been synthesized in the presence of structure-modifying agents, and then characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption-desorption at -196 °C, NH₃ thermoprogrammed desorption (NH₃⁻TPD), CO₂ thermoprogrammed desorption (CO₂⁻TPD), and X-ray photoelectron spectroscopy (XPS). These porous materials were evaluated in the furfural hydrogenation through the Meerwein-Ponndorf-Verley (MPV) reaction. The catalytic results indicate that the catalyst synthesized under hydrothermal conditions and adding a pore expander agent is more active and selective to furfuryl alcohol.

Porous Silicon-Based Catalysts for the Dehydration of Glycerol to High Value-Added Products.

Increasing worldwide biodiesel production has led to the generation of an important glycerol surplus, which needs to be valorized in order to improve the economic and environmental sustainability of the biodiesel industry. In this context, glycerol dehydration to acrolein by acid catalysis appears to be a potential route of glycerol valorization, since acrolein is an important intermediate for many chemical industries. The main drawback of this catalytic process is catalyst deactivation.

Selective Production of 2-Methylfuran by Gas-Phase Hydrogenation of Furfural on Copper Incorporated by Complexation in Mesoporous Silica Catalysts.

Copper species have been incorporated in mesoporous silica (MS) through complexation with the amine groups of dodecylamine, which was used as a structure-directing agent in the synthesis. A series of Cu/SiO catalysts (xCu-MS) with copper loadings (x) from 2.5 to 20 wt % was synthesized and evaluated in the gas-phase hydrogenation of furfural (FUR).

Dehydration of xylose to furfural over MCM-41-supported niobium-oxide catalysts.

A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by using XRD, N2 adsorption-desorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of D-xylose to furfural. Under the operating conditions used all materials are active in the dehydration of xylose to furfural (excluding the MCM-41 silica support). The xylose conversion increases with increasing Nb2 O5 content.

Evaluation of Cu-PPHs as active catalysts for the SCR process to control NOx emissions from heavy duty diesel vehicles.

Copper based catalysts supported on mesoporous materials, which were in turn based on a surfactant expanded zirconium phosphate for the formation of silica galleries in the interlayer space, were prepared by the impregnation method. They were then characterised and tested in the selective catalytic reduction of NO with ammonia as active catalysts for the control of the NOx emissions from heavy duty vehicles. Copper catalysts displayed a high catalytic performance, even in the presence of 14% (v/v) of H2O and 100 ppm of SO2.