Hydrodeoxygenation Of Palmitic Acid Research Articles

Structural and electronic effects boosting Ni-doped Mo2C catalyst toward high-efficiency C[sbnd]O/C[sbnd]C bonds cleavage

The selective cleavage of CO and CC is facing a challenge in the field of catalysis. In the present work, we studied the influence of doped Ni on the structure and electronic properties, as well as the selective CO/CC bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo2C catalyst. The catalytic activity on Ni doped Mo2C with TOF of 6.9 × 103 h−1 is much superior to intrinsic Mo2C catalyst, which is also higher than most noble metal catalysts. Structurally, the doped Ni raises the active particle dispersion and the coordination numbers of Mo species (Mo-C and Mo-O), improves the graphitization degree to promote the electron transfer, and increases the amount of Lewis and Brønsted acid, which are responsible for the excellent hydrodeoxygenation performance. The Ni promotes simultaneously CO and CC bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping. These findings contribute to the understanding of the nature of Ni-doped Mo2C on the roles as catalytic active sites for CO and CC bonds cleavage.

Rationally control the path of hydrodeoxygenation of palmitic acid over Ni/red-mud catalysts by surface decoration of oxophilic MoOx species

Red mud supported Ni (Ni/RM) catalysts have been explored to the hydrodeoxygenation (HDO) of palmitic acid, however, the decarbonylation (DCO)/decarboxylation (DCO2) is dominant. Therefore, the modification the oxophilic nature of catalysts can significantly impact their path of HDO and selectivity to aim products. Herein, MoOx-decorated Ni-Mo/RM catalysts with a hierarchical flower-like micro/nanostructure were prepared and applied in the HDO of palmitic acid. The effect of MoOx addition was investigated to control the path of HDO, resulting in the changing of carbon number distribution of the product. Combined with several comprehensive structural characterizations and catalytic HDO test, it is shown that the surface defective MoOx species and FeOx species near the metallic sites could significantly facilitate the C-O bond weakening, generated more direct deoxygenation product (hexadecane). Whereas the excessive Mo loading leads to clear altering of surface chemistry (i.e., decrease of specific surface area, pore volume and Mo0 species, increase of reduction temperature and CO2 adsorption, uneven dispersion, and agglomeration of Ni species), resulting in the decrease of palmitic acid conversion. As the main oxide in RM, Fe2O3, Al2O3 and SiO2 were used as supports to load Ni-Mo bimetals respectively to explore the contribution of different components in RM to the distribution of hydrodeoxygenation products of palmitic acid.

Selective production of alkanes and fatty alcohol via hydrodeoxygenation of palmitic acid over red mud-supported nickel catalysts

Production of valuable chemicals and fuels from waste animal fat and vegetable oils can serve as alternatives to fossil energy. In this study, the selective production of alkanes and higher fatty alcohol via hydrodeoxygenation (HDO) of palmitic acid over red mud-supported nickel catalysts (Ni/RM) was reported. Meanwhile, the study has investigated the effect of Ni loading, reaction temperature, hydrogen pressure on the HDO of palmitic acid, analyzed the reusability of Ni/RM and explored the possible reaction mechanism. The results show that palmitic acid is completely converted over 7%Ni/RM. The selectivity of fatty alcohol and alkanes are 92.54% (260 °C) and 100% (300 °C), respectively. Ni/RM has shown the highest catalytic performance as compared to commercial Ni/SiO2 and Ni/γ-Al2O3 catalysts. The 7%Ni/RM also demonstrates stable catalytic performance after multiple times of reuse. Moreover, hexadecanol plays an important role in hydrodeoxygenation, decarbonylation, and decarboxylation routes.

Production of diesel-like hydrocarbons via hydrodeoxygenation of palmitic acid over Ni/TS-1 catalyst

Hydrodeoxygenation of lipids is a promising method to produce diesel-like hydrocarbons. In this work, NiO/TS-1 and Ni/TS-1 catalysts were synthesized, and the catalytic hydrodeoxygenation of palmitic acid to produce diesel-like hydrocarbons was investigated. The effect of reaction time (2–10 h) and H2 pressure (1–5 MPa) on the production of diesel-like hydrocarbons were also studied in detail. Finally, a possible reaction route was proposed. The results showed that catalytic hydrodeoxygenation performance is affected by the valence of active component Ni. Ni/TS-1 shows better catalytic performance than NiO/TS-1 in terms of palmitic acid conversion and alkanes selectivity. Under the optimal experimental conditions (260 °C, 4 MPa, 10 h, 400 rpm), the palmitic acid conversion and pentadecane selectivity over Ni/TS-1 are 100% and 91.6%, respectively. It is found that hexadecanol is an important intermediate in the hydrodeoxygenation of palmitic acid.

Hydrodeoxygenation of palmitic acid over zeolite-supported nickel catalysts

In this study, Ni and Ni/Mo catalysts supported on zeolite ZSM-5, aka Ni/ZSM-5 and Ni-Mo(R)/ZSM-5, were successfully prepared by the incipient wetness impregnation method to hydrotreat heterogeneously the palmitic acid with an aim for the production of green diesel. Various instruments, such as XRD, SEM, BET, XPS, NH3-TPD and H2-TPR, were employed to characterize these catalysts. The hydrodeoxygenation (HDO) reaction of palmitic acid was carried out in an autoclave at 300 °C with an initial pressure of hydrogen at 35 bar. With Ni-Mo(R)/ZSM-5 catalysts priorly reduced in H2 at 500 °C, the conversion of palmitic acid could reach near 99% after 4 h of HDO reaction at 300 °C. Furthermore, a significant portion of isomerized paraffins appeared in the product, as revealed by GC–MS. That is, both hydrodeoxygenation and hydroisomerization reactions took place conjointly on palmitic acid with Ni-Mo(R)/ZSM-5 catalysts.

Ultra-low loading of Ni in catalysts supported on mesoporous SiO2 and their performance in hydrodeoxygenation of palmitic acid

Ni catalysts supported on KIT-5 are attractive heterogeneous catalysts for hydrodeoxygenation of biomass feedstocks.

Chemoselective hydrodeoxygenation of palmitic acid to diesel-like hydrocarbons over Ni/MoO2@Mo2CTx catalyst with extraordinary synergic effect

Chemoselective hydrodeoxygenation (HDO) of lipids to diesel-like hydrocarbons is important for biomass to biofuel conversion. Here we design a new Ni-based catalyst (Ni/MoO2@Mo2CTx) with extraordinary catalytic performance in the HDO of palmitic acid. To relieve the loss of C atom for Ni-based catalyst, partial oxidation of Mo2CTx MXene was used as a novel support. As a result, the catalytic activity and selectivity ratio of hexadecane/pentadecane (C16/C15) were enhanced over Ni/MoO2@Mo2CTx catalyst, and the major product of palmitic acid HDO is C16, demonstrating a high C atom economy. This facilitated catalytic performance may be ascribed to the synergic effect of metal Ni, Mo2CTx MXene as well as MoO2 active sites. The palmitic acid (–COOH) can convert into hexadecanal (–CHO) and hexadecanol (–CH2OH) over Ni/MoO2@Mo2CTx catalyst in the initial stage. The metal Ni further contributes to the hydrogenation of the hexadecanal to C15 with the cleavage of C–C bonds by decarbonylation (DCO) route. MoO2 nanoparticles obtained from Mo2CTx oxidation accelerate the scission of C–O bonds of the hexadecanol to improve the selectivity of C16 by hydrogenation-dehydration route.

Development of bio-inspired supports based on Ca–SiO2 and their use in hydrodeoxygenation of palmitic acid

Novel supports were developed for biomass conversion. A series of Ca–SiO2 materials were synthesized with a bio-inspired methodology. We used CaCO3 and CaSO4 for the modification of high surface area SiO2 to introduce basic and acid sites into the support. These two calcium sources were impregnated into the SiO2 in the presence of l-Alanine or l-Glycine. Both amino acids are able to bind calcium and those were used as a bio-inspiration procedure for changing the surface properties of SiO2. A series of MoO3 catalysts were prepared on the different supports and those were tested in the hydrodeoxygenation (HDO) of palmitic acid (PA). We found the formation of crystalline phases at the support surface due to the Ca addition. CaCO3 crystalline structure disappeared after the preparation of the catalysts because a new compound is formed, CaMoO4, while CaSO4 is not able to form any new compound with MoO3. Surface basicity and acidity were characterized by FT-IR using CO2 or pyridine adsorbed on the materials, respectively. We found that acidity plays a major role in the HDO of PA. Highly active MoO3-based catalysts were obtained by using SiO2–CaSO4 or SiO2–CaCO3 supports combined with amino acids.

MoO3-based catalysts supported on SiO2 and their performance in hydrodeoxygenation

A series of MoO3 catalysts supported on SiO2 were prepared. The aim of this work is to understand the factors that determine their catalytic performance in hydrodeoxygenation (HDO) of fatty acids. The impregnation of Mo species was carried out by using citric acid (CA) or malonic acid (MA) in aqueous solutions. The use of organic acids resulted in changing the oxidation states of Mo in the materials. The performance of the catalyst prepared with CA was the best in this series. We found that oxidation states of Mo species play a major role in the HDO of palmitic acid.

Synthesis of Renewable Diesel Range Alkanes by Hydrodeoxygenation of Palmitic Acid over 5% Ni/CNTs under Mild Conditions

Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound of bio-oil under a mild condition of 240 °C reaction temperature and 2 MPa H2 pressure. The experimental results revealed that the main reaction product was pentadecane (yield of 89.64%) at an optimum palmitic acid conversion of 97.25% via the hydrodecarbonylation (HDC) process. The deoxygenation mechanism for palmitic acid conversion was also investigated. This study provides technical parameters and a theoretical basis for further industrialization in the bio-oil upgrading process.