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This study introduces a novel Cu-based catalyst for the selective hydrogenolysis of glycerol to 1,2-propanediol, synthesized by impregnating mesoporous γ-alumina with Cu and Fe. Characterization was performed using various analytical methods, and tests were conducted in a tubular continuous reactor under specific conditions. Iron was found to have multiple modifying effects, influencing the modification of Cu clusters on the catalyst surface and the radial Cu concentration profile inside the particles. A low Fe/Cu ratio resulted in an almost egg-shell Cu profile, whereas higher Fe levels produced a more uniform distribution. Interestingly, minor Fe additions led to larger Cu clusters, while higher amounts resulted in smaller clusters and decreased glycerol conversion. The effect of Fe on Cu clusters size, acid sites concentration, and Cu radial profile, as well as the influence of these parameters on the glycerol conversion and selectivity towards 1,2-PD are discussed in this study. [Display omitted] • Mechanically resistant, cheap and very effective Cu based catalyst for the selective hydrogenolysis of glycerol. • Selectivity to 1,2-propanediol above 90 % was achieved. • Activity enhancement by modification with Fe addition was described and clarified in detail. • The catalyst has industrial potential for phasing out fossil resources and substituting with renewables. [ABSTRACT FROM AUTHOR]

A process of transforming hydrotalcite, containing Cu-Zn-Al (2:1:1) to a catalysts for selective hydrogenolysis of glycerol to 1,2-propanediol has been studied. A two steps process, consisted of the calcination at increased temperature and subsequent reduction with hydrogen, as well as a one step process, in which the hydrotalcite was heated at hydrogen atmosphere so the calcination and reduction were joined to one operation, were verified experimentally. The influence of the temperature in the calcination step in the two steps process on composition, texture and catalytic properties of the active form of catalyst has been studied in detail. X Ray diffraction, thermogravimetric analyses, nitrogen physisorption, mercury porosimetry, temperature-programmed reduction and high-resolution transmission electron microscopy were used for the catalysts characterization. A study of calcination of a Cu-Zn-Al containing hydrotalcite at different temperatures showed, that at temperature ending with 350 °C, predominantly amorphous, mixed oxides containing phase was formed. The most active and most selective catalyst was obtained by the reduction of this amorphous oxide phase. In contrary, highly crystalline material was obtained at higher calcination temperatures, i.e at 450 or 700 °C respectively, but the activity of the reduced form of these crystalline oxides was lower. It was also proven, that by simultaneous calcination and reduction, a catalyst of the same activity and even better selectivity towards 1,2-propanediol could be prepared, comparing with the catalyst prepared by the two steps method. [ABSTRACT FROM AUTHOR]

• Nitridation temperature play a crucial role in catalyst properties and activity. • At the optimised conditions, Co-Mo nitride catalyst show a HDS efficiency up to 99.0%. • At the optimised conditions, Co-Mo nitride catalyst show a HDN efficiency up to 84.0%. Sulfur-free transition metal carbide and nitride catalysts have been shown to be reasonable substitutes for sulfidic catalysts for the hydrotreating middle distillates and vegetable oils. However, their catalyst activity is still lower than commercial catalysts. In this paper, we build on our previous research by studying the synthesis and testing of nine sulfur-free Al 2 O 3 -supported Co-Mo nitride catalysts for the hydrotreating of atmospheric gasoil and its blends with rapeseed oil (25 wt.%) under industrial conditions (330–350 °C, 5.5 MPa, WHSV 1–2 h−1). Nitration temperatures play the most significant role in the synthesis and activity of the catalyst, obtaining a CoMoNx catalyst whose catalytic behaviour competes with the current commercial sulfidic Ni-Mo or Co-Mo catalysts (reduction of sulfur and nitrogen content up to 99.0 and 84.0%, respectively). Thus, our results allow us to evaluate and define the most suitable synthesis conditions for preparing high activity sulfur-free Al 2 O 3 -supported Co-Mo nitride catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we studied the effect of molybdenum precursors and the synthesis conditions on the final phase composition of bulk and supported molybdenum carbides and nitrides. Ammonium heptamolybdate, its mixture with hexamethylenetetramine, and their complex were used as the precursors at different temperatures. It was investigated that the synthesis of the target molybdenum nitrides strongly depended on the structure of the precursor and temperature conditions, while the synthesis of carbide samples always led to the target phase composition. Unlike the carbide samples, where the α-Mo2C phase was predominant, the mixture of β-Mo2N, MoO2 with a small amount of metal molybdenum was generally formed during the nitridation. All supported samples showed a very good dispersion of the carbide or nitride phases. [ABSTRACT FROM AUTHOR]

Kinetics of guaiacol hydrodeoxygenation (HDO) was studied using supported MoxC–SBA-15 and as a comparison 5 wt% Pt/C under 30 bar hydrogen at 200 °C and 300 °C. Catalyst characterization was done by a range of physical methods including also determination of the amount of coke and the nature of adsorbed species. Pt/C gave 2-methoxycyclohexanol as the main product, whereas Mo2C–SBA-15 promoted direct deoxygenation exhibiting also strong adsorption of guaiacol on the catalyst surface and formation of oligomers. Thermodynamics of guaiacol HDO was elucidated and the reaction network was proposed based on which kinetic modelling was done. [ABSTRACT FROM AUTHOR]

Transition metal nitrides, carbides and phosphides have the potential to replace the expensive and hazardous catalysts typically used for the conversion of fatty acids. However, there has been little research on the influence of treatment conditions and precursor nature on the properties of such catalytic systems. To better understand these dependencies, we synthesized a number of Mo catalysts by temperature‐programmed reduction (700‐900 °C; CH4/N2, N2/H2) using ammonium heptamolybdate, diammonium phosphate and hexamethylenetetramine (HMT) as Mo, C, N and P sources. The presence of HMT in the precursor mixtures ensured the synthesis of pure phase Mo2C, Mo2N and MoP. Catalytic activity in the (hydro)deoxygenation of stearic acid (240 min; 360 °C; 50 bar of H2) decreased in the following order: Mo2C>Mo2N>MoP. However, all of the studied Mo‐based catalysts showed good deoxygenation efficiency and, thus, represent excellent alternatives to traditional noble and sulfur‐containing catalysts. [ABSTRACT FROM AUTHOR]

• Glycerol hydrogenolysis to propylene glycol on reduced Cu-Zn-Al oxides was studied. • Zn presence influenced Cu particles size as well as their surface. • Zn effect had its maximum at the molar ratio of Zn/(Cu+Al) = 0.35. • Excess of Zn led to the formation of ZnO and deterioration of Cu surface. • Acidic centres were not primarily important for the reaction mechanism. A series of Cu-Zn-Al oxide catalysts reduced in H 2 was tested in glycerol hydrogenolysis in a stirred batch autoclave at 230°C. The catalysts were prepared by the precipitation – calcination method from layered double hydroxides (LDH) structures. The oxide forms of the catalysts were obtained by calcination of these structures at programmed temperatures, up to 350°C. The catalysts were characterized by the following methods: X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermogravimetric analyses (TGA), N 2 -physisorption and temperature programmed desorption of ammonia (NH 3 -TPD). It was found that Zn plays acts as a structure modifier, influencing Cu dispersion and particle size. Consequently, Zn has an impact on the catalyst activity. In particular, the Zn effect had its maximum at the concentration corresponding to a ratio of Zn/(Cu+Al) = 0.35 where conversion of 65% and the selectivity to 1,2-propanediol of 70% was achieved after 60 min of reaction time. [Display omitted] [ABSTRACT FROM AUTHOR]