Effect of sintering on the catalytic functionalities of MOS2/Al2O3 catalysts

Effect of sintering on physico-chemical and catalytic properties of Mo, Co-Mo, Ni-Mosupported on -Al₂O₃ is reported. Such effects on hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodeoxygenation (HDO) are investigated as a function of sintering temperature. The results indicated that HDS and HYD have different optimum calcination temperatures and these functionalities originate from different sites. The results are discussed in the light of molybdenum sulfide dispersion, promotional effects and phase transformations of active component, promoters and support.     

1,6-己二醇国内市场分析

1,6-己二醇（HDO）是一种新兴的精细化工原料。本文对国内1,6-己二醇的生产、技术、价格及消费情况进行了分析,预计未来几年HDO的消费量将呈现高速发展之势,市场份额也将不断增加。     

二硫化钼催化剂的制备与应用

综述了二硫化钼催化剂的物理化学性质以及国内外的几种制备方法,包括工业天然法和化学合成法。简要介绍了载体对催化剂的一些影响;从加氢脱硫、加氢脱氧及催化加氢几个方面对二硫化钼催化剂的应用进行了论述;对二硫化钼的形态,嵌入不同金属的MoS2催化剂在应用中对反应的影响及催化加氢机理进行了简要叙述。     

Hydrogenolysis and hydrodeoxygenation of lignin in a two-step process to produce hydrocarbons and alkylphenols

Valuable fuels and chemicals production from biomass with high yields is always a big challenge in the energy utilization field. Herein, a two-step process for the catalytic conversion of lignin was proposed to form the fuels. In the first step, the depolymerization of lignin occurred efficiently via the hydrogenolysis reaction, resulting in 19.2% aromatic monomers under the catalysis of Pd/C and CrCl₃. The catalysts exhibited a synergistic effect on the cleavage of β-O-4 bonds and the hydrogenation procedure, which prevented the condensation of intermediate products remarkably. Afterwards, the aromatic monomers were extracted out with octane solvent successfully (extraction degree 89.7%) and then used as a substrate in a second hydrodeoxygenation (HDO) step. Product mixture composed of 26.5% hydrocarbons (increased from 5.5%) and 49.7% alkylphenols (increased from 42.9%) were obtained after the HDO upgrading, which exhibited high potential to be used as fuels. This two-step approach is very promising to be a practical chemical engineering process for the fuel production from lignin.     

Hydrodeoxygenation of methyl esters on sulphided NiMo/γ-Al2O3 and CoMo/γ-Al2O3 catalysts

Wood-derived bio-oil contains high amounts of compounds with different oxygen-containing functional groups that must be removed to improve the fuel characteristics. Elimination of oxygen from carboxylic groups was studied with model compounds, methyl heptanoate and methyl hexanoate, on sulphided NiMo/γ-Al₂O₃ and CoMo/γ-Al₂O₃ catalysts in a flow reactor. Catalyst performances and reaction schemes were addressed. Aliphatic methyl esters produced hydrocarbons via three main paths: The first path gave alcohols followed by dehydration to hydrocarbons. Deesterification yielded an alcohol and a carboxylic acid in the second path. Carboxylic acid was further converted to hydrocarbons either directly or with an alcohol intermediate. Decarboxylation of the esters led to hydrocarbons in the third path. No oxygen-containing compounds were detected at complete conversions. However, the product distributions changed with time, even at complete conversions, indicating that both catalysts deactivated under the studied conditions.     

Refinement of the kinetic model for guaiacol hydrodeoxygenation over platinum catalysts

In our prior work (Ind Eng Chem Res, 2015, 54, 10638-10644), hydrodeoxygenation (HDO) kinetics of guaiacol, a well-known model compound of bio-oil, over Pt/AC (activated carbon) catalysts were investigated under integral operating conditions. It was found that the pseudo-homogeneous plug-flow model utilizing these kinetics describes the experimental observations well (with normalized RMS error = 7.6%). In the present work, under differential operating conditions instead, we refine the kinetic model for the same reaction network over the same catalyst. We show that among the five reaction steps in the network, the reaction order of one step differs from our prior work, while the orders remain unchanged for the other four steps. The activation energies of two steps differ from our prior values by 10–15 kJ/mol, and for the other three steps remain essentially consistent with our prior work. The kinetic parameters from the present work are used to predict fixed-bed reactor performance under integral operating conditions as well. The comparison between experimental and predicted values for both the prior and new sets of data is excellent and even better than our prior model (with reduced normalized RMS error = 4.2%). The kinetic analysis additionally proposed that the direct and indirect pathways of phenol formation from guaiacol HDO depend on guaiacol conversion values. The present work demonstrates that kinetic expressions and parameters obtained from a gradientless differential reactor are more reliable and can be used to successfully predict integral reactor performance data.     

Vapour phase hydrodeoxygenation of furfural into fuel grade compounds on NiPMoS catalyst: Synergetic effect of NiP and laponite support

The goal of the research would be to comprehend synergetic effect, additionally the Ni promotion level in the unsupported and Laponite supported NiMoS & NiPMoS catalysts. In this process, the sulfide catalysts were synthesized by a soft chemical approach under hydrothermal condition and also the Ni promotion was enhanced with the addition of phosphorus. The catalysts were characterized predicated on XRD, N₂–physisorption, TPR, H₂ pulse chemisorption, and XPS analysis. The catalysts were evaluated and compared for HDO of furfural (Hemicellulosic model compound) on temperature ranges from 503 K to 583 K under 20 bar H₂ pressurized reaction condition in the vapour phase reactor. The characterization of phosphorus added NiMoS catalysts exhibited improved textural properties with a suitable surface morphology, extraordinary stability, metal-support interaction, and metal dispersion on the support. The catalytic activity results revealed that the unsupported and Laponite supported NiPMoS catalyst performed better HDO conversion of furfural with remarkable high stability, producing deoxygenated hydrocarbons. Thereby, an innovative new unsupported and Laponite supported NiPMoS catalysts were successfully developed. The synergetic factor, intrinsic rate associated with the catalysts were correlated with improved textural properties, surface morphology, percentage of sulfidation of NiMo species, a large amount of acid sites, and dissociated hydrogen species of the catalysts.     

Finding a suitable thermodynamic model and phase equilibria for hydrodeoxygenation reactions of methyl heptanoate

Replacement of fossil fuels with biomass-based components is of increasing public and scientific interest. Unfortunately, most biomass-based compounds contain oxygen and oxygen content must be diminished before use of the compounds as fuel. Removal is usually done catalytically, with hydrogen supplied to convert the oxygen to water. Hydrodeoxygenation (HDO) of biomass-based compounds is often studied with model compounds, and the system investigated here was methyl heptanoate + m-xylene. Modeling of the reaction kinetics requires that behavior of the reaction mixture as a function of reaction time must be described. A suitable thermodynamic model for non-ideal system at high pressure and temperature is needed, and this demands correct modeling of the solubility of hydrogen and the water of reaction. For validation of the thermodynamic models isothermal vapor–liquid equilibrium (VLE) for the methyl heptanoate + m-xylene system was measured at 398.15 K and 408.15 K with a circulation still. The experimental VLE exhibited slight negative deviation from Raoult’s law. No azeotropic behavior was found. The experimental VLE results were correlated with the Wilson model with temperature-dependent parameters and used in testing of the SRK, original UNIFAC, UNIFAC-Dortmund, and PSRK predictive models. PSRK was preferred for further estimations. All VLE measurements passed the point consistency tests. Simulated reaction conditions for HDO of methyl heptanoate at the initial and final points were calculated to determine the effect of vapor–liquid equilibrium on the composition of reaction mixtures.     

Guaiacol derivatives and inhibiting species adsorption over MoS2 and CoMoS catalysts under HDO conditions: A DFT study

We have investigated using DFT calculations the η¹ adsorption of guaiacol, phenol, anisole and phenol over CoMoS and MoS₂ phases under HDO conditions. This adsorption mode should lead to a direct deoxygenation (DDO) reaction, which is low hydrogen-consuming. The most stable mode is an adsorption through the OH group of the molecule. The calculation of adsorption Gibbs free energies of inhibiting compounds (H₂O, H₂S, and CO) which can be present under reaction conditions shows that these molecules adsorb more strongly than oxygenated compounds, which suggests that CO will be a major inhibitor of the HDO process of real feeds.     

Hydrodeoxygenation of guaiacol on noble metal catalysts

Hydrodeoxygenation (HDO) performed at high temperatures and pressures is one alternative for upgrading of pyrolysis oils from biomass. Studies on zirconia-supported mono- and bimetallic noble metal (Rh, Pd, Pt) catalysts showed these catalysts to be active and selective in the hydrogenation of guaiacol (GUA) at 100 °C and in the HDO of GUA at 300 °C. GUA was used as model compound for wood-based pyrolysis oil. At the temperatures tested, the performance of the noble metal catalysts, especially the Rh-containing catalysts was similar or better than that of the conventional sulfided CoMo/Al₂O₃ catalyst. The carbon deposition on the noble metal catalysts was lower than that on the sulfided CoMo/Al₂O₃ catalyst. The performance of the Rh-containing catalysts in the reactions of GUA at the tested conditions demonstrates their potential in the upgrading of wood-based pyrolysis oils.