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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]

Bifunctional palladium-based catalysts with zeolite supports were investigated in phenol hydroalkylation, representing high-potential model reaction for transformation of lignocellulose-derived compounds to automotive and jet fuels. Conversion of phenol correlated with the amount of accessible acid sites and textural properties of the solid acid support: under the same reaction conditions and at the same Pd loading. The highest phenol conversions (99–100%) were obtained for large-pore zeolite Beta and mesopore-containing MCM-36/56 materials. The selectivity towards the targeted cyclohexylcyclohexane on different supports decreased in the following order Beta (57%) > MCM-36 (42%) ≈ MCM-56 (37%) > MCM-22 (20%), while the contribution of undesired reaction termination through formation of non-reactive cyclohexane was more pronounced for the expanded MCM-36/56 based catalysts. Substrate consumption after 60 min over the least active MCM-22-based catalysts increased with increasing Pd content as follows 27% (0.3 wt % Pd), 80% (0.5 wt % Pd) and 98% (0.7 wt % Pd). High activity of Pd/Beta catalysts was not vitiated even by sintering effects being the most pronounced for Beta as a support. [ABSTRACT FROM AUTHOR]

Sulfur-free Mo carbide catalysts supported on Al 2 O 3 and TiO 2 have shown good activity during the co-processing of middle distillates with vegetable oils in prior studies. However, their hydrotreating activity is low compared with that of conventional hydrotreating catalysts. To increase the hydrotreating effectiveness, promoter metals, such as Ni or Co, can be added. This paper describes an extensive study on the use of four sulfur-free Ni-Mo and Co-Mo carbide catalysts (supported on Al 2 O 3 and TiO 2) for the hydrotreatment of atmospheric gasoil (AGO) and co-processing with rapeseed oil (RSO). The tests were conducted in a fixed bed reactor unit at 330–350 °C, 5.5 MPa, a weigh hourly space velocity (WHSV) = 1–2 h−1, and AGO/RSO of 100/0, 95/5, 90/10, and 75/25 wt.%. Analogous to conventional hydrotreatment catalysts, adding the promotor metals significantly increased the product quality and the hydrodesulfurisation and hydrodenitrogenation efficiencies at higher temperatures or at lower WHSVs. In the case of RSO co-processing, all the tested catalysts promoted the hydrodeoxygenation pathway instead of (hydro)decarboxylation/decarbonylation with an insignificant decrease in the hydrodesulfurization efficiency at lower AGO/RSO ratios. Therefore, our results suggest that promoting Mo carbide catalysts with Ni or Co significantly improves their catalytic properties, making them more competitive with conventional hydrotreating catalysts. [ABSTRACT FROM AUTHOR]

Sulfur-free Al2O3-supported Co-Mo and Ni-Mo carbide catalysts have shown a significant catalyst activity during hydrotreating. According to our previous studies, a catalyst modification with phosphorus is a promising way to improve catalyst activity. In this paper, we build on our previous research by studying six sulfur-free Al2O3-supported and phosphorus-modified (0.5, 1.5 and 2.5 wt%) Co-Mo and Ni-Mo carbide catalysts for the hydrotreating of atmospheric gas oil and its co-processing with atmospheric gas oil (5, 10 and 25 wt%) under industrial conditions (330–350 °C, 5.5 MPa, WHSV 1–2 h−1). Adding 0.5 wt% of phosphorus increases catalyst acidity and reducibility, positively affecting catalyst activity (HDS 10–20%, HDN 10–15%). During co-processing, adding 0.5 wt% of phosphorus to the catalysts also offers better stability results even at the highest ratio (75/25). Our results enable us to evaluate the effect of phosphorus addition on catalyst properties and activity, developing a suitable alternative to commercial catalysts. [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]

• 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]

Generally, the commercial catalysts for hydrotreatment in refineries are supported sulfide transition-metal-based catalysts. However, the co-processing of vegetable oils reduces their hydrodesulfurization (HDS) efficiency by leaching sulfur from the active sites of the catalyst. The present work reports the use of six sulfur-free MoCx and MoNx catalysts (supporter with Al 2 O 3 , TiO 2 or ZrO 2) for the hydrotreatment of atmospheric gasoil (AGO) and co-processing of rapeseed oil (RSO – 5, 10 and 25 wt%). The screening tests were carried out in a fixed bed reactor at industrial operating conditions (330–350 °C, 5.5 MPa, WHSV = 1–2 h−1). Higher reaction temperatures and lower WHSV had a positive effect on catalyst activity and product quality. In case of co-processing, the hydrodeoxygenation reaction mechanism was found to be dominant, producing n-C 16 and n-C 18 n-alkanes at all AGO/RSO ratios used. Overall, our results suggest that alumina supported catalysts are the most promising materials, exhibiting a combination of excellent stability, high activity and no negative effects on HDS efficiency during AGO/RSO co-processing. [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]