M. Olga Guerrero-Pérez

New Reaction: Conversion of Glycerol into Acrylonitrile

Glycerol is a major by-product from methanolysis during theproduction of biodiesel. Thus, it is an increasingly importantmolecule in the context of renewable biomass resources toprovide energy and chemical intermediates. However, the de-velopment of selective glycerol-based catalytic processes is amajor challenge as a result of their low selectivity.

Raman spectroscopy during catalytic operations with on-line activity measurement (operando spectroscopy): a method for understanding the active centres of cations supported on porous materials

Raman spectroscopy with on-line activity measurement (operando Raman spectroscopy) is used to reach a molecular understanding of the structure–activity relationship of supported vanadium oxide catalysts during alkane selective oxidation and ammoxidation reactions. The advantage of the operando methodology is that the molecular structures are recorded during true catalytic operation, thus affording information about the structures relevant to the catalytic performance. It is shown that efficient propane ammoxidation requires both surface mono-oxo vanadium oxide species and SbVO4 phases.

Recent Inventions in Glycerol Transformations and Processing

Many patents claiming new processes for the conversion of glycerol into valuable-added chemicals are appearing in recent years as a result of glycerol availability since it is the main by-product in the biodiesel production and in other processes concerning biomass as raw material. In a future biorefinery glycerol will remain as a platform molecule. Present review describes a selection of such patents and shows the potential of glycerol as raw material in such future chemical industries (biorefineries).

Niobia-supported Sb–V–O catalysts for propane ammoxidation: effect of catalyst composition on the selectivity to acrylonitrile

The effect of the Sb/V atomic ratio and of the total Sbu2006+u2006V coverage for the ammoxidation of propane to acrylonitrile on niobia-supported V–Sb oxide catalysts is reported. In all cases, acrylonitrile is produced along with propylene and CO2. Depending on the Sbu2006+u2006V coverage two different activity behaviours are reported: below the Sbu2006+u2006V dispersion limit on niobia, the system is predominantly selective to acrylonitrile, this fact has been attributed to exposed Nb centres and to V–Nb–O mixed oxide phases promoted by Sb. At Sbu2006+u2006V loading above monolayer coverage, the system is also selective to acrylonitrile but product distribution is clearly different and characteristic of SbVO4 phases, affording selectivities to propylene similar to those to acrylonitrile.

Efficient microwave-promoted acrylonitrile sustainable synthesis from glycerol

Solvent-free microwave-activation, in the liquid phase using an alumina supported V-Sb-O catalyst, affords highly efficient conversion (47%) of glycerol into acrylonitrile under mild conditions, short reaction times and in the absence of any solvent; in addition, it increases selectivity (>80%) compared to conventional thermal activation.

Tuning of Active Sites in NiNbO Catalysts for the Direct Conversion of Ethane to Acetonitrile or Ethylene

NiO nanoparticles that are highly active for the ethane activation have been prepared. These nanoparticles have been dispersed on the surface of two different Nb2O5 materials by using a novel dry nanodispersion method. This article describes the characterization and catalytic behavior of both series of catalysts as well as the nature of the active sites required for the transformation of ethane into acetonitrile and/or ethylene. It is demonstrated how such active sites present in the catalysts are obtained through this novel dry mixing method. The catalysts obtained are promising catalytic materials for both, ethane ammoxidation and oxidative dehydration (ODH) reactions.

In situ Raman studies during sulfidation, and operando Raman-GC during ammoxidation reaction using nickel-containing catalysts: a valuable tool to identify the transformations of catalytic species

Ni-containing catalysts are investigated under reaction conditions for two different cases, during sulfidation, with Ni-Mo based catalysts, and during ammoxidation reaction, with the Ni-Nb catalysts. It is shown how Raman spectroscopy can follow some of the transformations of these catalysts upon different treatments. For the NiMo/Al(2)O(3)-SiO(2) system it was possible to identify some of the sulfided Mo species formed during the sulfidation of the oxide precursors, while for the bulk Ni-Nb oxide catalysts the simultaneous reaction-Raman results strongly suggest that the incipient interaction between niobium and nickel oxides at low Nb/Ni atomic ratios is directly related to catalytic activity, and that a larger size well-defined NiNb(2)O(6) mixed oxide phase is not active for this reaction. Moreover, the promotion by niobium doping appears to be limited to a moderate niobium loading. It was found that in situ and operando Raman are valuable techniques that allowed the identification of active Mo-S and Ni-Nb species under reaction conditions, and that are not stable under air atmospheres.

Niobia-Supported Nanoscaled Bulk-NiO Catalysts for the Ammoxidation of Ethane into Acetonitrile

Two series of supported nanoscaled NiO catalysts have been prepared using Nb2O5 supports with different surface areas. NiO nanoparticles interacting with Ni–O–Nb mixed phases are active and selective for ethane ammoxidation; both are required in order to have an active and selective catalyst. In this paper we report the dispersion of NiO nanoparticles on two Nb2O5 supports in order to generate an active phase for ethane ammoxidation. The use of a support stabilizes NiO nanoparticles, which otherwise would sinter. This work shows how the activity can be modulated by the size of the NiO nanoparticles and by the NiO/Ni–Nb–O ratio, which depends on the nickel coverage and support surface area. The catalysts obtained are very promising for ethane ammoxidation reaction.Graphical Abstract

Performance of NiO and Ni–Nb–O active phases during the ethane ammoxidation into acetonitrile

There is a need to develop catalysts for the direct ammoxidation of ethane to acetonitrile. This work reports a series of bulk Ni–Nb–O catalysts with increasing niobium content, analysing the structure and the effect on acidity and redox properties and how these relate to Ni–Nb interaction. Niobium doping affects NiO lattice leading to progressively smaller unit cell sizes. The Nb/Ni atomic ratio determines the formation of two Nb–Ni–O mixed phases identified by HRTEM, and which Raman bands are identified near 850 cm−1 and 800 cm−1 for a Nb-poor phase and near 800 cm−1 for a Nb-rich Ni–Nb–O one.

Propane Versus Ethane Ammoxidation on Mixed Oxide Catalytic Systems: Influence of the Alkane Structure

Catalysts from three different catalytic systems, Ni–Nb–O, Mo–V–Nb–Te–O and Sb–V–O, have been prepared, characterized, and tested during both ethane and propane ammoxidation reactions, in order to obtain acetonitrile and acrylonitrile, respectively. The catalytic results show that Mo–V–Nb–Te–O and Sb–V–O catalyze propane ammoxidation but are inactive for ethane ammoxidation whereas Ni–Nb–O catalysts catalyze both, ethane and propane ammoxidation. The activity results, and the characterization of fresh and used catalysts along with some data from previous studies, indicate that the ammoxidation reaction mechanism that occurs in these catalytic systems is different. In the case of Mo–V–Nb–Te–O and Sb–V–O, two active sites appear to be involved. In the case of Ni–Nb–O catalysts, only one site seems to be involved, which underlines that the mechanism is different and take place via a different intermediate. These catalysts activate the methyl groups in ethane, on the contrary, neither ethane nor ethylene appear to adsorb on the Mo–V–Nb–Te–O and Sb–V–O active sites.Graphical Abstract