Selective Hydrogenolysis Research Articles

The crucial role of interaction between WOx and Ti–Si composite oxide for selective hydrogenolysis of glycerol to 1,3-propanediol

Hydrogenolysis of glycerol, a by-product in the preparation of biodiesel, to synthesize 1,3-propanediol has attracted widespread attention because of its environmental and economic benefits. How to activate the secondary hydroxyl group in glycerol to suppress the formation of 1,2-propanediol is still challenging. Pt-WOx-based catalyst has been popularly studied due to high 1,3-propanediol selectivity but its stability is unsatisfactory. Here we synthesized an oxygen vacancy-rich support (HTSO) consisting of Ti–Si composite oxide to stabilize WOx species. The glycerol conversion and 1,3-propanediol selectivity of optimized 2Pt-10WOx/HTSO-1.0 catalyst achieved 40% and 46%, respectively. Moreover, the catalytic performance remained stable over 10 reaction cycles. Based on the investigation of the structure-performance relationship of catalysts, the excellent catalytic performance was attributed to the anchoring of WOx species by oxygen vacancies, thus stabilizing the chemical valence of W. The correlation between acid sites and catalyst performance was intensively investigated. This work provides an alternative approach for preparing stable Pt-WOx-based catalysts and deepens the knowledge of the correlation between acidic sites and 1,3-propanediol selectivity.

Improved nickel nanocatalysts for selective cleavage of lignin model compounds and lignin

The selective hydrogenolysis of lignin offers a promising avenue for converting lignin into valuable chemicals and fuels. However, the development of highly active catalysts for this process remains challenging. In this study, a series of Nix/Al2O3 catalysts were synthesized by calcining and reducing layered double hydroxides (LDHs) precursors. These catalysts were evaluated for their effectiveness in catalyzing the conversion of lignin-derived model compounds (2-phenoxy-1-phenylethanol and diphenyl ether). Remarkably, the optimized Ni3/Al2O3 catalyst demonstrated exceptional performance in cleaving C–O bonds, achieving complete conversion with high selectivity for monomers product under reaction conditions of 200 °C, 1 MPa H2, and 1 h. The catalyst's outstanding performance can be attributed to its relatively large specific surface area, Ni loading exceeding 50 wt%, well-dispersed Ni metal particles, abundant surface oxygen vacancies, and a significant number of acid sites. Additionally, the hydrogenolysis of lignin using the Ni3/Al2O3 catalyst resulted in a substantial production of monophenols (15.0 wt%). This study introduces a novel approach for tailoring highly active Ni nanocatalysts and highlights the capability of Nix/Al2O3 catalysts to efficiently cleave C–O bonds in lignin under mild reaction conditions.

Selective Hydrogenolysis of Furfuryl Alcohol to Pentanediol over Pt Supported on MgO

The catalytic conversion of naturally rich and renewable biomass into high-value chemicals is of great significance for pursuing a sustainable future and a green economy. The preparation of pentanediol from furfuryl alcohol is an important means of high-value conversion of biomass. The Pt-based catalyst supported on MgO was applied to the selective hydrogenation of biomass furfuryl alcohol to prepare pentanediol. By adjusting parameters such as catalyst loading, reduction temperature, reaction temperature, and pressure, a highly active catalyst was designed and the optimal catalytic hydrogenation conditions were determined. The hydrogenation experiment results showed that the selectivity of the 2Pt/MgO-200 catalyst for 1,2-pentanediol and 1,5-pentanediol reached 59.4% and 15.2%, respectively, under 160 °C and 1 MPa hydrogen pressure. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), CO2-temperature programmed desorption (CO2-TPD), and other methods. The characterization results indicate that the reduction temperature has a significant impact on the metal Pt, and an appropriate reduction temperature is beneficial for the hydrogenation performance of the catalyst. In addition, the basic sites on the carrier are also another important factor affecting the activity of the catalyst. In addition, stability tests were conducted on the catalyst, and the reasons for catalyst deactivation were studied using methods such as thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The results showed that the activity of the catalyst decreased after five cycles, and the deactivation was due to the hydrolysis of the carrier, the increase in metal particle size, and the surface adsorption of organic matter.

Boosting catalytic activity of Ni/ZrO2 by introducing MoO3 on selective hydrogenolysis of lignin

Conversion of renewable lignin to value-added aromatic chemicals presents a broad prospect to achieve the goals of “carbon neutrality”. In this work, an efficient approach is proposed for selective hydrogenolysis of lignin to valuable 4-propyl syringol in the presence of cost-effective catalyst of yNi/ZrO2-xMoO3. When the lignin hydrogenolysis is performed with 15Ni/ZrO2-10MoO3, 15.4% yield of monophenols is achieved, which is approximately twice as that from the 15Ni/ZrO2 catalytic system (7.8%). Importantly, 33.1% of these monophenols are identified as 4-propyl syringol (4-PS), a versatile fine chemical. An extensive characterization of the modified catalysts by means of XRD, nitrogen adsorption–desorption isotherm, SEM, TEM, XPS, NH3-TPD, CO2-TPD, and H2-TPR, confirms that the introduction of MoO3 changes the primary phase of ZrO2 and the acidity/basicity properties of catalyst. As a result, an enhanced cleavage of the C-O linkage between S-lignin and other units is demonstrated, which consequently contributes to the good selectivity of 4-propyl syringol. Therefore, this work provides a new insight for producing bulk aromatic chemicals via a sustainable route.

Tailoring Cu immobilized MCM-41-based mesostructured catalysts for selective hydrogenolysis of biomass-derived furfural

The CuO-supported MCM-41 catalysts were prepared using a simple incipient wet impregnation method. The catalysts were investigated for hydrogenation of furfural to furfuryl alcohol synthesis. Among all the catalysts, the 2.5% CuO/MCM-41 catalyst shows the best catalytic performance with 92.5% conversion and 89% selectivity of furfuryl alcohol at 210 °C. The catalyst also demonstrated a high turnover frequency (TOF) of 154.4 h−1. The 2.5% CuO/MCM-41 catalyst remained stable for up to 20 h during the time on stream.

Tailoring Cu/Hydroxyapatite Catalysts for Selective Hydrogenolysis of Biomass Derived Levulinic Acid to γ-Valerolactone Biofuel Additive

Background: Sustainable synthesis of γ-valerolactone (GVL) from levulinic acid (LA) offers a sustainable approach to converting biomass-derived feedstocks into valuable chemicals and fuel additves. Cu-Hydroxyapatite (Cu-HAp) catalysts are potential candidates for vapor-phase hydrogenation of LA to GVL due to their enhanced catalytic activity and selectivity through Cu nanoparticle support. Objective: This study aimed to investigate the catalytic performance of Cu-HAp catalysts in the hydrogenation of levulinic acid to γ-valerolactone. The primary goal was to optimize reaction conditions and assess the enhanced catalytic activity and selectivity Methods: The influence of copper loading, reaction temperature, and catalyst stability was evaluated. Moreover, the effect of time on stream (TOS) on LA conversion and GVL selectivity was examined by the best optimised Cu/HAp catalyst. Results: Cu-HAp catalysts exhibited favorable catalytic performance, with optimal conditions at approximately 5wt% copper loading. At this loading, maximum LA conversion (60%) and GVL selectivity (90%) were achieved after 8 hours on the stream at 265°C and 0.1 MPa conditions. Conclusion: The study demonstrates the efficacy of Cu-HAp catalysts for the hydrogenation of levulinic acid to γ-valerolactone. The findings indicate that as the copper loading increases from 2 to 20 wt%, the conversion of LA and the selectivity to GVL both decline. The analysis further implies that the dispersion of Cu species corresponds directly to the activity observed during the LA hydrogenation. The conversion of LA rises with a higher reaction temperature ranging from 250-320°C, although the selectivity of GVL decreases above 265°C. The catalyst's stability is crucial for maintaining efficient catalytic activity over time, with observed deactivation attributed to Cu metal particle aggregation and coke formation on active sites. The findings contribute to the development of robust catalyst systems for biomass-derived chemical transformations.

A new method for green production of 2-aminomethylpiperidine from bio-renewable 2,5-bis(aminomethyl)furan

A new method for synthesizing 2-aminomethylpiperidine by selective hydrogenolysis of bio-renewable 2,5-bis(aminomethyl)furan was developed. The yield of 2-aminomethylpiperidine can reach 72% under mild conditions at 140 °C and 1 MPa H2 pressure.

Selective hydrogenolysis of 5-hydroxymethylfurfural to 2,5-dimethylfuran with high yield over bimetallic Ru-Co/AC catalysts.

Catalytic hydrogenolysis of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) has become a hot topic in the bioenergy field in recent years. It remains a challenge to mediate the activation/hydrogenation/hydrogenolysis of C-O and C[double bond, length as m-dash]O bonds of HMF at high temperatures. Herein, bimetallic Ru-Co/AC catalysts were prepared by the "two-step" reduction method and were used to catalyze the hydrogenolysis of HMF to DMF. The effects of different reduction methods, Ru/Co ratios, and Ru loading on the catalytic performances of the Ru-Co/AC catalysts were investigated, and the physicochemical properties of the catalysts were characterized by TEM, XPS, H2-TPR, etc. It was found that the catalysts reduced by the "two-step" reduction method exhibited better catalytic activities than those fabricated by a single H2 or NaBH4 reduction method. The introduction of Co metals promoted the dispersion of Ru nanoparticles (NPs) on AC and the transfer of electrons from Co to Ru, thereby improving the catalytic activity. An excellent yield of DMF up to 97.9% and 98.7% conversion of HMF were achieved in a short time (1.5 h) under the optimal conditions (200 °C, 1 MPa). Furthermore, the possible reaction pathway for the hydrogenolysis of HMF to DMF over 5%Ru-1%Co/AC catalyst is also discussed. The work shows that the Ru-Co/AC catalysts have great potentials for the conversion of HMF into liquid fuel DMF.

An Ag-promoted Co/Al2O3 catalyst without reduction pretreatment for the selective hydrogenolysis of high-concentration glycerol to 1,2-propanediol

Ag facilitates the in situ reduction of Co3O4 to form low-oxidizing-degree CoOx and oxygen vacancies (Ovac.) during reaction, promoting a high efficiency of the prereduction-free CoAg/Al2O3 catalyst for hydrogenolysis of glycerol to 1,2-propanediol.

Production of propyl 4-hydroxybenzoate via selective hydrogenolysis of lignin catalyzed by Ni/MFI-ns

An efficient approach is proposed for producing the value-added petrochemical propyl-4-hydroxybenzoate via the selective hydrogenolysis of lignin catalyzed by Ni/MFI-ns featuring enhanced mass diffusion.

Selective hydrogenolysis of the Csp2-O bond in the furan ring using hydride-proton pairs derived from hydrogen spillover.

Selective hydrogenolysis of biomass-derived furanic compounds is a promising approach for synthesizing aliphatic polyols by opening the furan ring. However, there remains a significant need for highly efficient catalysts that selectively target the Csp2-O bond in the furan ring, as well as for a deeper understanding of the fundamental atomistic mechanisms behind these reactions. In this study, we present the use of Pt-Fe bimetallic catalysts supported on layered double hydroxides [PtFe x /LDH] for the hydrogenolysis of furanic compounds into aliphatic alcohols, achieving over 90% selectivity toward diols and triols. Our findings reveal that the synergy between Pt nanoparticles, atomically dispersed Pt sites and the support facilitates the formation of hydride-proton pair at the Pt δ+⋯O2- Lewis acid-base unit of PtFe x /LDH through hydrogen spillover. The hydride specifically targets the Csp2-O bond in the furan ring, initiating an SN2 reaction and ring cleavage. Moreover, the presence of Fe improves the yield of desired alcohols by inhibiting the adsorption of vinyl groups, thereby suppressing the hydrogenation of the furan ring.

Selective hydrogenolysis of furfural to 1,2-pentanediol over a Pt–Fe/MT catalyst under mild conditions

A Pt–Fe bimetallic catalyst is developed to produce 1,2-pentanediol from furfural under mild conditions of 140 °C and 0.1 MPa H2, affording by far the highest production rate.

Interfacial synergy within bimetallic oxide promotes selective hydrogenolysis of furfuryl alcohol to 1,5-pentanediol

Cobalt-based catalysts have displayed intrinsic activity for selective hydrogenolysis of furfural alcohol (FFA) to 1,5-pentanediol (1,5-PDO), but how to efficiently enhance 1,5-PDO selectivity remain a challenge. We prepared a series of CoPtLa-Hx catalysts by different reduction temperatures, and found the interfacial synergy within the bimetallic oxide CoOx-PtOx of the CoPtLa-H5 catalyst not only boosted the dispersion of Co species and Pt species, also increased electronic interactions within the bimetallic oxide which promoted the formation of the content of Co2+ that are critical to C-O bond rupture of FFA. The interfacial synergy significantly enhanced the 1,5-PDO yield (40.3 %) and favored high catalyst stability. We found that the formations of 1,5-PDO, 1,2-PDO and tetrahydrofurfuryl alcohol (THFA) are competing reactions, which is helpful to the design of highly selective catalysts towards the conversion FFA to 1,5-PDO.

Ru nanoparticles supported on various metal-modified (La, Zr, Cr, Ce and Ga) α-Al2O3 for the selective hydrogenolysis of lignin and its derived ethers

Controlling the C-O bond hydrogenolysis while suppressing the direct hydrogenation of aromatic rings in lignin-derived ethers is critical and challenging for the utilization of lignin. Herein, a series of metal-modified (La, Zr, Cr, Ce and Ga) α-Al2O3-supported Ru-based catalysts were synthesized for the conversion of diphenyl ether (DPE). The catalyst characterizations demonstrate that the metal modification cannot change the chemical valence of Ru but promotes the dispersion of Ru nanoparticles and adjusts the adsorption state of DPE. The results indicate that the metal modification inhibits the arenes hydrogenation at low temperatures but facilitates the C-O bond cleavage during heating (at low H2 pressures or an inert atmosphere). Ru-Cr/α-Al2O3 shows the highest reaction rate for DPE conversion at 1 MPa Ar and 200 °C. Moreover, Ru-Cr/α-Al2O3 not only efficiently converts different lignin model compounds by hydrogenolysis, but also achieves the controlled depolymerization of real lignin to generate guaiacols under mild conditions.

Synergy of electronic and steric effects of Br-Ni catalysts for selective hydrogenolysis of diphenyl ether to phenol

Selective hydrogenolysis of 4-O-5 bond in lignin under relatively mild conditions is an important strategy for the production of valuable aromatic products, e.g. phenols, from renewable carbon resources. However, the easy saturation of benzene rings under reductive conditions over metal catalyst reduces the selectivity to aromatics. In this work, we investigated the effect of bromination of supported Ni nanoparticles on the phenol selectivity during the hydrogenolysis of diphenyl ether (DPE), a commonly used lignin model compound. Compared with the unmodified catalysts, Br-Ni/Al2O3 catalyst derived from Ni-Al layered double oxides exhibits enhanced phenol selectivity (37% vs. 15%) under similar DPE conversions (60%). Various characterizations including transmission electron microscopy (TEM), in-situ X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and CO-Fourier transform infrared spectroscopy (FTIR) indicate that Br preferentially located at the terrace site of Ni nanoparticles, deactivating the continuous Ni sites for benzene ring hydrogenation. In addition, the electron-withdrawing effect of Br creates positively charged Ni sites at the corners, facilitating the hydrogenolysis of C–O aryl ether bonds. During the hydrogenation of real lignin, the selective poisoning and electronic effects introduced by Br synergistically increased the yield of phenols from 12.20% on the initial Ni/Al2O3 to 30.47% over the Br-Ni/Al2O3 catalyst. This work provides an advanced strategy for the catalytic valorization of lignin by halogen modified metal-based catalysts.

Techno-commercial viability of glycerol valorization to 1,2- and 1,3-propanediol using pinch technology

Glycerol is a low-value by-product in biodiesel industries and an important platform chemical in biorefinery with vast derivative potentials. 1,2- and 1,3-Propanediol (PDO) are vital polymer precursors. Valorizing glycerol to PDOs is thus a promising approach for producing renewable chemicals and improving the economics of biodiesel industries. Therefore, this work demonstrated the techno-economic feasibility of PDOs for 100–2000 metric tons per day glycerol feed rate. 1,2-PDO was produced by selective hydrogenolysis of glycerol, while microbial batch and fed-batch fermentation of glycerol was considered for manufacturing 1,3-PDO with the co-production of 2,3-butanediol and ethanol. Pinch analysis was applied for process integration that reduced utility demands by around 19% for 1,2-PDO and 12–16% for 1,3-PDO. However, utilities were still major operating costs in these processes. Besides, utility consumptions and capital expenditures were considerably higher for 1,3-PDO by batch fermentation than 1,2-PDO due to low glycerol concentration (50 g/L). 1,3-PDO production cost (USD 3.42/kg) by batch fermentation was thus much more than 1,2-PDO (USD 0.98/kg). The minimum unitary selling price was USD 1.15 for 1,2-PDO and USD 4.90 for 1,3-PDO (batch) for 8.5% rate of return and five years payback period. However, the microbial 1,3-PDO produced by fed-batch fermentation was economically viable, with USD 0.78 and USD 1.02 as unitary production costs and minimum selling price.

Ruthenium catalysts supported on activated carbon from corncob waste for selective hydrogenolysis of C–O bonds in lignin-derived aromatic compounds

Selective hydrogenolysis of C–O bonds in lignin is regarded as an important process to produce high value-added chemicals and biofuels. Herein, high-performance Ru-based catalysts (Ru/AC) supported on activated carbon (AC) derived from corncob waste were prepared by a simple impregnation method. The optimal 5%Ru/AC possessed enormous specific surface area, well-developed porosity, high metal dispersion, small Ru particle size and strong metal-support interaction, showing a marvelous catalytic performance in the hydrogenolysis of diphenyl ether, benzyl phenyl ether and phenylethyl phenyl ether with different kinds of C–O bonds under mild conditions. Besides, various phenolic compounds were selectively hydrogenated into cycloalkanols and cycloalkanes over 5%Ru/AC, indicating the excellent catalytic activity in aromatic ring hydrogenation of this catalyst. In addition, high conversion of diphenyl ether and high selectivity of monomeric products were well maintained after employing this catalyst at least three times. The construction and application of the ingenious 5%Ru/AC catalyst highlighted a promising approach to the value-added utilization of lignin-derived aromatic compounds.

Pt-Loaded Nb─W Metal Composite Oxide for Selective Cleavage of Secondary C─O Bonds.

Selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) is recognized as one of the most promising reactions for the valorization of biomass. Precise activation of C─O bonds of glycerol molecule is the key step to realize the high yield of catalytic conversion. Here, a Pt-loaded Nb-W composite oxides with crystallographic shear phase for the precise activation and cleavage of secondary C─O (C(2)─O) bonds are first reported. The developed Nb14 W3 O44 with uniform structure possesses arrays of W-O-Nb active sites that totally distinct from individual WOx or NbOx species, which is superior to the adsorption and activation of C(2)─O bonds. The Nb14 W3 O44 support with rich reversible redox couples also promotes the electron feedback ability of Pt and enhances its interaction with Pt nanoparticles, resulting in high activity for H2 dissociation and hydrogenation. All these favorable factors confer the Pt/Nb14 W3 O44 excellent performance for selective hydrogenolysis of glycerol to 1,3-PDO with the yield of 75.2% exceeding the record of 66%, paying the way for the commercial development of biomass conversion. The reported catalysts or approach can also be adopted to create a family of Nb-W metal composite oxides for other catalytic reactions requiring selective C─O bond activation and cleavage.

Selective and efficient production of 1,5-pentanediol from tetrahydrofurfuryl alcohol using Ni-La(OH)3 catalysts

Biomass-derived furfural and its derivatives are promising feedstocks for producing valuable C5 diols by catalytic hydrolysis. However, this process requires selective ring opening of tetrahydrofurfuryl alcohol (THFA) to 1,5-pentanediol, which is challenging. Here we report efficient route for this conversion using Ni-La(OH)3 catalysts prepared by a green co-precipitation-hydrothermal method. We show that these catalysts can achieve up to 91.7% yield and 94.6% selectivity of 1,5-pentanediol from THFA under mild conditions. We elucidate the key role of the La(OH)3 phase, the basic sites and the Nin+-O-La3+ structure of the catalysts in promoting the selective hydrogenolysis and ring opening of THFA. We also demonstrate that the co-dehydrogenation of secondary alcohols enables lower reaction pressure and longer catalyst lifetime. Our work provides a sustainable and environmentally benign approach for producing 1,5-pentanediol from biomass-based furfural and its derivatives, which has potential applications in polymer synthesis and green chemistry.

SMSI-induced charge transfer for selective hydrogenolysis of polyolefins

The in-depth mechanism of the emerging Ru-catalyzed polyolefin hydrogenolysis remains unclear. Here, we overcome this challenge by constructing a strong metal-support interaction (SMSI) system based on Ru/TiO2 catalysts. With the increase of SMSI intensity, electrons are transferred from the TiOx capping layer to the Ru species. This effect facilitates the key steps of hydrogenation/desorption, while having little effect on the dehydrogenation and C–C cracking elementary reactions. As a result, the catalyst with higher hydrogenation capability prone to proceed hydrogenation and desorption step, thus suppressing cascade C–C cracking and avoiding the production of low value methane. The catalyst with the strongest SMSI effect exhibits a liquid fuel yield of 89.4% at ∼100% solid conversion. The SMSI effect also enables the catalysts with superior stability, so it can also efficiently upcycle commercial polyolefins. This work provides an in-depth understanding of the effects of metal-support interactions on polyolefin hydrogenolysis and paves the way for catalyst design.