MPa H2 Pressure Research Articles

Precisely Tailoring the Second Coordination Sphere of a Cobalt Single-Atom Catalyst for Selective Hydrogenation of Halogenated Nitroarenes.

The development of highly efficient and cost-effective nonprecious metal catalysts for the selective hydrogenation of halogenated nitroarenes is very appealing yet challenging. Here, we demonstrate that the hydrogenation activity and selectivity of Co single-atom catalyst (SAC) can be tuned by tailoring the structure of second coordination sphere via P doping. As revealed by synchrotron radiation-based X-ray absorption spectroscopy characterizations, such a P doping on N-coordinated Co SAC results in the unsymmetric Co-N4P1 coordination structure. With a combination of experimental characterizations and theoretical simulations, we find that tailoring the second coordination sphere can greatly improve H2 dissociation and product desorption. As a result, the Co-N4P1 SAC exhibits superior activity, selectivity and stability for the hydrogenation of halogenated nitroarenes to corresponding amines (20 examples, >99% yields) at 80 oC under 0.5 MPa H2 pressure, significantly outperforming most heterogeneous catalysts reported in the literature. We expect that this work opens a new avenue for the design of highly efficient nonprecious metal SACs for important hydrogenation reactions.

Precisely Tailoring the Second Coordination Sphere of a Cobalt Single‐Atom Catalyst for Selective Hydrogenation of Halogenated Nitroarenes

The development of highly efficient and cost‐effective nonprecious metal catalysts for the selective hydrogenation of halogenated nitroarenes is very appealing yet challenging. Here, we demonstrate that the hydrogenation activity and selectivity of Co single‐atom catalyst (SAC) can be tuned by tailoring the structure of second coordination sphere via P doping. As revealed by synchrotron radiation‐based X‐ray absorption spectroscopy characterizations, such a P doping on N‐coordinated Co SAC results in the unsymmetric Co‐N4P1 coordination structure. With a combination of experimental characterizations and theoretical simulations, we find that tailoring the second coordination sphere can greatly improve H2 dissociation and product desorption. As a result, the Co‐N4P1 SAC exhibits superior activity, selectivity and stability for the hydrogenation of halogenated nitroarenes to corresponding amines (20 examples, >99% yields) at 80 oC under 0.5 MPa H2 pressure, significantly outperforming most heterogeneous catalysts reported in the literature. We expect that this work opens a new avenue for the design of highly efficient nonprecious metal SACs for important hydrogenation reactions.

A very simple synthesis of defect-rich PdAg nanosponges for highly selective hydrogenation of furfural

Furfuryl alcohol (FA) is an important chemical and has extensive applications in varied fields. To realize the highly selective hydrogenation of furfural (FF) to produce FA, the key is the preparation of the catalysts with excellent performance. Herein, a very simple wet chemical method is developed for the one-step preparation of PdAg nanosponges (NSs). Specifically, with Pd(OAc)2 and AgNO3 as precursors, and ethylene glycol (EG) as both solvent and reducing agent, PdAg NSs can be grown and assembled at mild temperature of 40 °C. Throughout the reaction, no any surfactants and additional reducing agents are applied. The as-prepared PdAg NSs possess 3D self-supported alloy structures, “clean” surface, abundant pores, high specific surface area and rich defects. In the FF hydrogenation reaction at 60 °C under 1.5 MPa H2 pressure in the mixed solvent of ethanol and water (1 : 4 in volume ratio), the self-supported PdAg-1 NSs (1 : 1 in Pd/Ag molar ratio) exhibit superior catalytic performance than other PdAg NSs, pure Pd sample and commercial Pd/C (10%). With PdAg-1 NSs as catalyst in the absence of support, 100% FF can be converted and the selectivity toward FA is as high as 97.1% at 36.0 h of reaction. After 4 cycles, PdAg-1 NSs still maintain the high catalytic activity in FF hydrogenation and high selectivity toward FA, which may originate from the 3D self-supported structures, high specific surface area, “clean” surface, rich defects and electronic synergistic effect between Pd and Ag. This simple fabrication of PdAg NSs introduces new ideas for the synthesis of other nanostructured bi- and multi-metallic catalysts for highly selective FF hydrogenation to FA and other advanced applications.

Modification of the hydrogen compression properties of Zr–Fe–Cr–V-based alloys through Ti doping

Hydrogen refueling stations typically rely on compressors to increase the pressure of hydrogen received from long-tube trailers, enabling efficient refill of hydrogen storage tanks. However, mechanical hydrogen compressors are unable to effectively harness residual hydrogen below 6 MPa in long-tube trailers. Herein, we developed a ZrFe2-based hydrogen compression alloy to enhance the hydrogen pressure that meets the input pressure requirement of mechanical hydrogen compressors. Specifically, the co-substitution of Cr and V for Fe was conducted to reduce the plateau slope and hysteresis, and Ti was introduced to partially substitute Zr to regulate the plateau pressure. The effects of Ti on the structure and hydrogen storage properties of Zr–Fe–Cr-based alloys have been investigated by first-principles calculations, wherein Zr1-xTixFe1.7Cr0.2V0.1 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were designed and synthesized. The optimized Zr0.8Ti0.2Fe1.7Cr0.2V0.1 alloy provided a hydrogen absorption capacity of 1.22 wt% under 3.88 MPa H2 pressure at 300 K and achieved an effective hydrogen compression capacity of 1.07 wt% at 355 K at an H2 desorption pressure of 6.36 MPa. This advancement holds great promise for the efficient utilization of residual hydrogen at approximately 6 MPa in long-tube trailers, thus leading to a significant improvement in hydrogen transportation efficiency.

Microwave-Assisted Efficient Intercalation for Fast Fabrication of High-Quality and Large-Size Single-Layer Ti3C2Tx Nanosheets.

A novel microwave-assisted intercalation (MAI) strategy is proposed for fast and efficient intercalation of layered MXene to prepare large-size single-layer MXene. After LiF-HCl etching of Ti3AlC2, the as-prepared multi-layer Ti3C2Tx (M-T) are intercalated with Li3AlF6 as an intercalator and ethylene glycol (EG) as a solvent under microwave irradiation for 5min. Furthermore, the dispersed high-quality large-sized single-layer Ti3C2Tx (S-T) nanosheets with a thickness of 1.66nm and a large lateral size over 20µm are achieved with a yield of over 60% after a further ultrasonic delamination followed by electrostatic precipitation, acid washing, and calcination. In addition, Pd/S-T composite catalyst, which is constructed with Pd nanoparticles supported on the as-prepared S-T nanosheets, exhibits an excellent performance for rapid and efficient selective hydrogenation of nitroarenes with H2 under a mild condition. At room temperature, full conversion of nitrobenzene and 100% aniline selectivity are achieved over Pd/S-T catalyst in 20min with 0.5MPa of H2 pressure. This work provides a novel method for facile, fast, and large-scale preparation of single-layer MXene and develops a new approach for constructing efficient nanocatalytic systems.

Selective Hydrodeoxygenation of Lignin-Derived Phenolic Monomers to Cyclohexanol over Tungstated Zirconia Supported Ruthenium Catalysts.

The selective hydrodeoxygenation (HDO) of lignin-derived methoxyphenols to cyclohexanol is one of the most significant transformation in biomass conversion since cyclohexanol is an important industrial raw material. This study has disclosed a series of tungstated zirconia with different Zr/W ratio supported Ru catalysts (Ru/xZrW, x means the molar ration of Zr/W) for the hydrodeoxygenation (HDO) of guaiacol to cyclohexanol. Among these catalysts, Ru/16ZrW has the best catalytic activity, which can achieve 92 % yield of cyclohexanol under the conditions of 180 °C and 1 MPa H2 pressure for 2 h (TOF 231 h-1). Compared with Ru/ZrO2, Ru/16ZrW has smaller particles, more dispersed and electron-rich Ru species, significant hydrogen spillover and more acid sites, which are the main reason for its excellent performance on this reaction. Apart from guaiacol, other methoxy substitution phenols and organosolv lignin can also be converted into cyclohexanol via hydrodeoxygenation reactions over this catalyst.

Furfural Hydrogenation Over Reduced Pure (LaBO3) and Substituted (LaB0.5B'0.5O3) (B, B': Fe, Co, Ni) Perovskites

AbstractA series of pure and 50 % substituted Fe‐containing (LaFeO3, LaFe0.5Ni0.5O3 and LaFe0.5Co0.5O3) and Co/Ni‐containing (LaCoO3, LaNiO3, and LaCo0.5Ni0.5O3) perovskites were used as precursors to synthesize metallic reduced catalysts to be tested for the liquid hydrogenation of furfural. The catalytic reaction was carried out in a batch reactor at 200 °C and 3.0 MPa of H2 pressure. The calcined perovskites and reduced catalysts were characterized by X‐ray diffraction (XRD), N2 physisorption at 77 K, temperature programmed reduction (H2‐TPR), temperature programmed CO2 and NH3 desorption (CO2‐TPD and NH3‐TPD), Atomic Absorption Spectroscopy (AAS) and X‐ray photoelectron spectroscopy (XPS) techniques. The LaCo0.5Ni0.5O3 reduced catalyst display the highest activity in furfural conversion, which was attributed to a cooperative effect between highly dispersed nickel and cobalt metal nanoparticles after reduction process. The effect of the nature of B‐cation have a high impact on the products selectivity in the hydrogenation of furfural, suggesting that enriched‐Ni metal surface was selectivity to tetrahydrofurfuryl alcohol, meanwhile enriched‐Co metal surface was selective to furfuryl alcohol formation, which was also supported with adsorption mode of furfural over the active sites obtained by quantum calculation.

Boosting the selective hydrogenation of biphenyl to cyclohexylbenzene over bimetallic Ni-Ru/SiO2 catalyst via enhancing strong metal-support interaction

Tuning the metal-support interaction (MSI) between highly dispersed nanosized metal particles and the support plays a pivotal role in the activity and selectivity of polyaromatics selective hydrogenation. In this work, the supported bimetallic Ni-Ru/SiO2-SEA catalyst was prepared by a strong electrostatic adsorption (SEA) strategy, and applied for the selective hydrogenation of biphenyl (BP) to cyclohexylbenzene (CHB). Compared to the catalysts prepared by the conventional incipient wetness impregnation method and Ni/SiO2-SEA, the significant effects of MSI and hydrogen spillover on Ni-Ru/SiO2-SEA facilitated the highly exposed and uniformly dispersed electron-deficient Niδ+ (0 < δ < 2) species, which could enhance adsorption and activation of the electron-withdrawing phenyl group and H2, thereby promoting the efficient and selective conversion of BP to CHB. At the conditions of 160 ℃ and 2 MPa H2 pressure, BP conversion over Ni-Ru/SiO2-SEA reached nearly 100 % within 3 h, achieving a remarkable selectivity of 97.9 % towards CHB, along with a high turnover frequency of 2756.9 h−1 for the active metallic Ni sites. Importantly, according to the kinetic simulations, the hydrogenation rate constant of Ni-Ru/SiO2-SEA was the highest (2.76 × 10-2 mol·g−1·h−1) among the employed catalysts. Moreover, after six consecutive cycles, no obvious decline in hydrogenation efficiency was observed, confirming the remarkable activity and stability of Ni-Ru/SiO2-SEA. Furthermore, the activation of BP and desorption of CHB pathway on the Niδ+ species were elaborated through temperature-programmed desorption characterization, highlighting the prominent contribution of MSI in enhancing the selective hydrogenation of polyaromatics.

Transition metal oxide nanocatalysts for the deoxygenation of palm oil to green diesel

This study investigated the hydrodeoxygenation of palm oil by different oxide nanocatalysts of transition metals α -Fe2O3, NiO, and NiFe2O4, which were synthesized by hot injection. All nanomaterials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and dynamic light dispersion. The catalytic evaluation was performed in a Parr-type reactor at 350°C, 3.5 MPa of H2 pressure, and 3 h of reaction. The liquid product obtained was analyzed by ultraviolet-visible light spectroscopy to identify the n-C16 generated during the reaction. The activity in the deoxygenation of fatty acids to produce n-C16 hydrocarbons has the following order: α-Fe2O3 &amp;lt; NiFe2O4 &amp;lt; NiO.

High‐Performance Supported Ru Catalysts for the Aqueous‐Phase Hydrogenation of Levulinic Acid to γ‐Valerolactone

Abstractγ‐Valerolactone (GVL) can be obtained by efficient hydrogenation of levulinic acid using ruthenium‐based catalysts in an aqueous medium. This paper reports an in‐depth study on the activity and selectivity of Ru catalysts supported on zirconia‐alumina, focusing on the effect of Ru concentration (0.5, 1.5 and 3 wt. % of Ru) and the selection of operational reaction variables. The results showed that the activity strongly depends on the number and oxidation state of the supported ruthenium particles. The most active catalyst, Ru3/ZA, presented the highest number of nanometric particles of zerovalent Ru and the highest number of acid sites. This catalyst gave ca. 100 % selectivity towards GVL, at high conversion of levulinic acid (over 99 %) under the best operating conditions evaluated (120 °C, 3 MPa H2 pressure, 1 h of reaction, and 0.1 g of catalyst). In addition, this catalyst kept high levels of conversion and selectivity after successive reuse cycles.

Optimizing Hydrogen Storage Pathways in Ti–Al Alloys through Controlled Oxygen Addition

In the present study, we aimed to destabilize the Ti–Al system with nonmetallic oxygen. The synthesis of α‐(Ti, Al)[O] starting from TiO2, Ti, and Al was carried out through the arc melting method, resulting in three different oxygen content levels, 3.4, 10, and 20 at%. The room temperature activation of α‐(Ti, Al)[O] was not successful, and the activation was performed at 300°C under 5 MPa H2 pressure. The structural changes after hydrogenation (maximum absorption capacity of 3.74 wt% hydrogen) arose from the transformation of α‐(Ti, Al)[O] to cubic (Ti, Al)[O]Hx (c‐(Ti, Al)[O]Hx); nonetheless, they recovered their original lattice parameters, which are meaningfully larger than those of α‐Ti, after dehydrogenation. The hydrogen storage capacities for various α‐(Ti, Al)[O] compositions generally decreased with increasing oxygen (3.4 and 10 at%) and aluminum content in the alloy. In contrast, for the compositions with a higher oxygen content of 20 at%, the hydrogen storage capacity slightly increased as the Al concentration increased: Ti0.790Al0.010O0.200 absorbed 2.91 wt% hydrogen, whereas Ti0.767Al0.033O0.200 absorbed 3.04 wt% hydrogen. The thermogravimetric analysis showed that samples with 20 at% O released hydrogen at lower temperatures even though the major phase after hydrogenation is c‐(Ti, Al)[O]Hx regardless of the oxygen content.

Preparation of SBA-15 supported Ru nanocatalysts by electrostatic adsorption-ultrasonic in situ reduction method and its catalytic performance for hydrogen storage of N-ethylcarbazole.

N-ethylcarbazole (NEC) is an ideal liquid organic hydrogen storage carrier. The development of efficient hydrogen storage catalysts can promote the large-scale application of this process. In this paper, SBA-15 supported Ru nanocatalysts (Ru/S15-SU) were synthesized by strong electrostatic adsorption (SEA)-ultrasonic in situ reduction method (UR). Ru/S15-SU was characterized by N2 adsorption-desorption, TEM, H2 temperature program reduction, FT-IR, XRD, and XPS analysis measures. The results showed that ultrafine Ru NPs were evenly distributed on the surface of SBA-15, and ultrasonic in situ reduction not only reduced Ru3+ to Ru0, but also produced a coordination effect between Ru and O, enhancing the interaction between Ru NPs and the carrier. Ru/S15-SU exhibited excellent catalytic performance in the hydrogenation reaction of NEC, and the hydrogen storage efficiency reached 99.31% at 130°C and 6 MPa H2 pressure, which is superior to that of commercial 5wt%Ru/Al2O3. The excellent catalytic hydrogenation performance can be attributed to the selective anchoring of ruthenium ions on the surface of SBA-15 via electrostatic adsorption, preventing the aggregation of Ru NPs and enhancing the interaction between SBA-15 and Ru NPs by ultrasonic in situ reduction. Ru/S15-SU had a lower NEC hydrogenation apparent activated energy (Ea) of 68.45 kJ/mol than 5wt%Ru/Al2O3 catalyst. This method provides a new approach for the green preparation of nanocatalysts without using any chemical reducing agents.

Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH2

The design of an excellent active catalyst to improve the sluggish kinetic and thermodynamic properties of magnesium hydride (MgH2) remains a great challenge to achieve its practical application. In this study, a novel Ni-Nb/rGO nanocomposite catalyst was successfully prepared by one-spot hydrothermal and subsequent calcination methods. The novel Ni-Nb/rGO nanocomposite exhibits an exceptional catalytic effect on improving MgH2 sorption properties. Specifically, the onset desorption temperature of MgH2 + 10 wt% Ni-Nb/rGO composite is reduced to 198 °C, much lower than that of undoped MgH2 (330 °C). Interestingly, the composite can release 5.0, 5.9, and 6.0 wt% H2 within 10 min at 245, 260, and 275 °C, respectively. Furthermore, the dehydrogenated MgH2 + 10 wt% Ni-Nb/rGO composite starts to absorb hydrogen even at room temperature with approximate 2.75 wt% H2 uptake at 75 °C under 3 MPa H2 pressure within 30 min and exhibits excellent stability by maintaining 6.0 wt% hydrogen content after 20 cycles at 300 °C. Chou's model suggests that the de/hydrogenation kinetics of Ni-Nb/rGO-modified MgH2 switches from surface penetration model to diffusion model at lower temperatures. Additionally, the activation energies (Ea) for the de/hydrogenation of MgH2 + 10 wt% Ni-Nb/rGO are reduced to 57.8 kJ/mol and 33.9 kJ/mol, which are significantly lower than those of undoped MgH2. The work demonstrates that the addition of a novel ternary Ni-Nb/rGO catalyst is an effective strategy to not only boost the sorption kinetics of MgH2 but also maintain its cycling property.

Improving catalytic performance and reusability of flower-like Co-B-P amorphous alloy nanobelts for the selective hydrogenation of furfural in water

Herein, active, low-cost, stable, and sustainable amorphous alloy Co-B-P nanobelts (NBs) are synthesized for the selective hydrogenation of furfural (FFR) to furfuryl alcohol (FFA) in H2O. The Co-B-P NBs are flower-like bundles of ultrathin nanosheets obtained by reducing Co ions in a layered liquid crystal using double-reducing agents at room temperature. The specific surface area, hydrogen adsorption capacity, surface states, and FFR selective hydrogenation performance of the Co-B-P NB catalyst can be modified via low-temperature plasma treatment. The treatment does not change the amorphous structure of Co-B-P NBs. In H2O, Co-B-P NBs treated with plasma at an appropriate power and time exhibit 100% FFR conversion and 95.8% FFA selectivity within 80 min at 80 °C and 1.2 MPa H2 pressure. Moreover, plasma treatment can be used to regenerate Co-B-P NB catalysts. The catalytic activity of Co-B-P NB catalysts can be restored using plasma treatment when it decreases because of their oxidation after several hydrogenation cycles.

Hydrangea-like NiO@KNbO3 as catalyst doping for MgH2: Boosting hydrogen storage performance

MgH2 is regarded as one of the most favorable materials for hydrogen storage caused by its safety, high efficiency, considerable capacity for storing hydrogen, and low cost. However, the application of this material is limited owing to subpar thermodynamics and kinetics, which can be improved via combination with other materials. A hydrangea-like NiO@KNbO3 was prepared by solvent thermal, hydrothermal, and calcination methods. Then, different amounts of NiO@KNbO3 (3, 5, 7, and 10 wt %) were added to MgH2 using ball-milling. MgH2 composite material doped with 5 wt % NiO@KNbO3 exhibits the most superior hydrogen storage performance, with a hydrogen absorption capacity of 4.95 wt % H2 within 5 min at 150 ℃ and 1.5 MPa H2 pressure. Furthermore, H2 release started approximately at 175 °C with 5.96 wt % H2 at 300 °C. The composite's H2 desorption activation energy was decreased to 71.75 kJ/mol. The Mg2NiH4/Mg2Ni generated in situ can serve as a "hydrogen pump" by creating numerous activation sites and pathways for hydrogen diffusion, thereby facilitating H2 dissociation during the process of hydrogen absorption. Additionally, the NiO@KNbO3-doped MgH2 samples exhibited excellent integrated hydrogen storage properties due to the combined effect of KNbO3 and the in situ formed NbO. The study provides clear evidence that NiO@KNbO3, a bimetallic oxide, can effectively enhance the hydrogen storage performance of MgH2 as an additive. Furthermore, the straightforward synthesis of NiO@KNbO3 offers guidance for the development of high-performance oxide catalysts that can improve the properties of MgH2.

Synergistic effect of surface Cu0 and Cu+ species on improved selective hydrogenation of furfural to furfuryl alcohol over hydrotalcite-derived CuxMg3Al oxides

In the selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL), it is important to develop a simple and cheap non-precious metal catalyst to replace the precious metal catalyst. Therefore, CuxMg3AlOy (x = 0.3, 0.5, 0.7, 0.9, 1.1) composite metal oxide catalysts were prepared by CuMgAl-LDHs as precursor for the selective hydrogenation of FAL to FOL. In this series of catalysts, Cu0.9Mg3AlOy has the best catalytic activity, with 99% FAL conversion and 98.4% selectivity under the mild reaction conditions of 1.6 MPa H2 pressure, 1.5 h and 120 ℃, and good reusability. XRD, TEM, H2-TPR, CO2-TPD, XPS and in-situ DRIFTS characterization were used to investigate the activate species for hydrogenation reaction. It can be proved that Cu2+ and Cu+ on the surface of CuxMg3AlOy can be partially reduced to the Cu0 species in-situ during the reaction, promoting the hydrogenation of FAL. Various studies confirm that Cu0 is mainly responsible for the activation and dissociation of H2, and both Cu0 and Cu+ are used to adsorb the carbonyl group in FAL to improve the selectivity of FOL. Moreover, the appropriate amount of the Cu0 and Cu+ species plays an important role in selective hydrogenation of FAL to FOL through their synergy.

Synthesis of Co―N―C catalysts from a glucose hydrochar and their efficient hydrogenation of nitrobenzene

A low-cost, green catalyst for nitrobenzene (NB) hydrogenation is needed for aniline production. We report the preparation of highly-dispersed Co particles supported on N-doped carbons by the hydrothermal treatment of glucose, followed by the pyrolysis of a mixture of urea, glucose hydrochar and cobalt nitrate in one-pot. The effect of the pyrolysis temperature on the microstructure of the catalysts was studied. Results indicated that the activity for NB hydrogenation was highly affected by the surface area, Co-loading level and Co-Nx coordination in the catalysts. Co@NCG-800 pyrolyzed at 800 °C with 10% Co in the precursor had extraordinary activity for NB hydrogenation, achieving full conversion and 99% aniline selectivity in isopropanol at 100 °C and 1 MPa H2 pressure for 2.5 h. NB conversion and aniline selectivity over the catalysts remained almost unchanged after six recycles, due to the strong coordination between the N- and Co-species. The reaction system showed not only a high NB activity but also a green and durable catalytic process, with easy operation, easy separation and catalyst reusability.

Copper nanoparticles encapsulated in a nanoporous carbon-based catalyst in the upgradation of γ-valerolactone to 1,4-pentanediol by selective hydrogenation

This research work introduces highly dispersed Cu nanoparticles encapsulated into a nanoporous carbon (Cu@C) structure as an efficient catalytic system in selective hydrogenation of γ-valerolactone (GVL) to 1,4-pentanediol. The nanoporous carbon support and the catalysts were synthesized by sequential novel methods and characterized extensively by using a combination of different analytical techniques to determine the phase, textural, morphology, nanoparticles size, and distribution analysis, and redox behavior. The designed Cu@C embedded catalysts show moderately high activity in GVL hydrogenation with different Cu loadings. The effect of copper loadings was found to be a significant parameter in gaining the best performance in GVL conversion. The copper nanoparticles were uniformly distributed over the nano-scaled carbon structure with active metallic Cu(111) sites with high dispersion and promote GVL hydrogenation, efficiently. Over a 5Cu@C catalyst exhibited the highest GVL conversion (∼91%) and 1,4-pentanediol selectivity (∼97%) at 200 °C for a 5 h reaction time under a 5 MPa H2 pressure. The dispersion of the active copper phase in combination with a smaller particle size and surface acidity is directly correlated with the catalytic performance activity. The effects of reaction parameters such as the reaction time, temperature, and H2 pressure were systematically investigated. Overall, Cu@C is a promising non-noble metal-based catalytic system for the upgradation of biomass-based platform molecules via selective hydrogenation.

Changes in structural parameters of SARA fractions during heavy oil hydrocracking using dispersed catalysts

Most of the characterization of SARA fractions of heavy crude oils during hydrocracking reactions is focused only on asphaltenes, and scarce works are devoted to analyze the differences in the structural parameters of all SARA fractions. In this work, a heavy crude oil is upgraded by non-catalytic and catalytic hydrocracking in a batch reactor at low severity conditions (3.9 MPa H2 pressure, 380 °C temperature, 800 rpm stirring rate, and 4 h reaction time). Three ore catalysts (hematite, magnetite and molybdenite) and one analytical grade catalyst (iron oxide) are employed. After reaction, the upgraded oils are first distilled and then separated into SARA fractions by the ASTM D86-16a and ASTM D2007-11 methods, respectively. NMR (1H and 13C), FTIR and GPC analyses are used to characterize SARA fractions before and after hydrocracking. The hydrocracking products exhibited a reduction in the average molecular weight of all SARA fractions as function of the hydrogenation capacity of each catalyst in the following order: Fe2O3 (analytical grade) > Molybdenite > Hematite > Magnetite. The structural parameters of saturates fraction remains unchanged except for the production of small length aliphatic chains from heavier fractions. For aromatics, resins and asphaltenes fractions, the number of aliphatic carbons is reduced due to dealkylation reactions increasing their aromaticity. For resins and asphaltenes fractions, hydrogenation and ring opening reactions are also carried out. Mo-based catalyst is mainly aimed at the conversion of asphaltenes, while the Fe-based catalysts focused on the conversion of resins.

Ultrauniform Ru Nanoclusters as Efficient Hydrogenation Catalysts for Phthalates

Cyclohexane dicarboxylic acid (CHDA) ester, a kind of environmental-friendly plasticizer, can be produced by phthalates hydrogenation. However, the synthesis of catalysts with high activity and selectivity is a challenge due to the stability of aromatic rings. In this work, a series of ultrauniform Ru nanoclusters supported by γ-Al2O3 are synthesized for the hydrogenation of diisononyl phthalate (DINP). Results show that the conversion of DINP and the selectivity of diisononyl-cyclohexane-1,2-dicarboxylate (DINCH) both reach 100% at 140 °C and 3 MPa H2 pressure. Diisononyl-cyclohexene-1,2-dicarboxylate (4H-DINP) and 1,2-cyclohexanedicarboxylate-7-methyloctyl ester are found; the hydrogenation reaction network of DINP is constructed. Alkali metal ions adsorbed on the surface of Ru nanoclusters prepared by the polyol method can stabilize Ru3+-Hδ− species by electrostatic interaction, thus affecting the hydrogenation activity of the catalyst, following the order of Li+ > Na+ > K+ > Cs+. Ru-based catalysts prepared by the polyol method have good prospects for application in phthalates hydrogenation.