Continuous Hydrogenation Research Articles

Front Cover: 5‐(Chloromethyl)Furfural as a Potential Source for Continuous Hydrogenation of 5‐(Hydroxymethyl)Furfural to 2,5‐Bis(Hydroxymethyl)Furan (ChemPlusChem 12/2022)

Front Cover: 5‐(Chloromethyl)Furfural as a Potential Source for Continuous Hydrogenation of 5‐(Hydroxymethyl)Furfural to 2,5‐Bis(Hydroxymethyl)Furan (ChemPlusChem 12/2022)

5-(Chloromethyl)Furfural as a Potential Source for Continuous Hydrogenation of 5-(Hydroxymethyl)Furfural to 2,5-Bis(Hydroxymethyl)Furan.

5-(Chloromethyl)furfural (CMF) is cheaper than sugars, because it can be obtained from biomass waste. Herein, the stepwise conversion of CMF to 2,5-bis(hydroxymethyl)furan (BHMF) via 5-(hydroxymethyl)furfural (HMF) was demonstrated for the first time. The purified CMF was hydrolyzed in continuous mode followed by extraction with ethyl acetate (EA), resulting in a HMF yield of 70 mol%. The following factors were assessed during continuous hydrogenation of the produced HMF: the presence of EA in the reaction solvent, HMF concentrations of up to 10 wt% in the feed, the mass production of mesoporous Cu-Al2 O3 (meso-CuA-kg), the shaping of meso-CuA-kg into cylindrical pellets, and the setup of the catalytic reactor. Through these efforts, the hydrogenation of HMF over meso-CuA-kg could be sustained for 100 h under the above optimized conditions, affording BHMF in 98 % yield. The approach described in this study can greatly contribute to the value-added transformation of CMF into HMF and BHMF.

Cover Feature: 3D‐Printed Structured Reactor with Integrated Single‐Atom Catalyst Film for Hydrogenation (ChemCatChem 14/2022)

The Cover Feature artistically shows the immobilization of a thin single-atom catalyst film on 3D-printed metal structures. As discussed in their Research Article, G. Vilé and co-workers first prepared a powdered copper single-atom catalyst. Then, they used 3D printing with an electron beam melting method to create a static mixer reactor coated with the single-atom catalyst film. The resulting catalytic reactor was used for continuous hydrogenations, with stable performance for several hours on stream. Industrially, structured catalytic reactors have several advantages compared with traditional packed-bed reactors, including low catalyst inventory, low pressure drop, and efficient mass/heat transfer. Thus, this work may have implications for the large-scale utilization of these catalytic materials. The authors thank Carmelo (Il Merlo) Garofalo for the illustration.More information can be found in the Research Article by G. Vilé and co-workers.

Fixed Bed Continuous Hydrogenations in Trickle Flow Mode: A Pharmaceutical Industry Perspective

Fixed Bed Continuous Hydrogenations in Trickle Flow Mode: A Pharmaceutical Industry Perspective

Nickel nanoparticles embedded in porous carbon-coated honeycomb ceramics: A potential monolithic catalyst for continuous hydrogenation reaction

The preparation method of porous carbon coated honeycomb ceramic monolithic catalysts is limited to traditional ideas. The porous carbon and the active metal particles are formed step by step. We have designed a novel preparation method and constructed a series of nickel-embedded porous carbon-coated (Ni@C) monolithic catalysts with different carbonization temperatures. Through the synchronous formation of porous carbon and active metal particles, the relationship between porous carbon and metal is changed from “supported” to “embedded”. The “embedded” structure between nickel particles and porous carbon formed at suitable carbonization temperature is an inseparable whole. Correlation characterization results show that the “embedded” structure has not changed the physical-chemical properties of porous carbon. However, the effect on the physical-chemical properties of nickel particles is very significant. Compared with conventional supported nickel-based monolithic catalysts (NiO/C), embedded nickel particles in the Ni@C monolithic catalyst have four characteristics. They are more uniform particle dispersion, smaller average particle size, more difficult to migrate and stable in metallic Ni0 form in air. Based on these advantages, Ni@C monolithic catalysts show better catalytic activity, stability and convenience in the continuous catalytic hydrogenation of aromatic nitro compounds.

Hydro-refining of coal-petroleum co-processing oil for potential clean jet fuels

A coal-petroleum co-processing oil (CPCO) and its distillation fraction at 180 °C (DF180) were subjected to catalytic hydro-desulfurization and hydrogenation with batch autoclave and fixed bed reactor respectively to produce potential jet fuels with low sulfur and high cyclanes content. The results show that sulfur content of CPCO reaches up to 2282 mg/L. After fractionation through distillation, the sulfur content in DF180 is reduced to 283.6 mg/L. When CPCO was hydrogenated at 280 °C with NiMoS/γ-Al2O3 catalyst, the content of sulfur-containing compounds (SCs) reduces and that of cyclanes increases. However, with higher hydrogenation temperatures or prolonged residence times, SCs content increased through their secondary reactions, i.e., the combination of S or HS with the fragments derived from hydro-cracking of CPCO. Meanwhile, the cyclanes content decreased. Similar phenomena were observed during hydrogenation of DF180 in autoclave. On the other hand, after 10 h continuous hydrogenation with NiMoS/γ-Al2O3, the content of sulfur was reduced to 9.1 mg/L and that of cyclanes increased to 29.9%, thus meeting the requirements for clean jet fuels. From these perspectives, this work provides an alternative means for producing clean jet fuels with CPCO liquids.

Atomically dispersed Ru(III) on N-doped mesoporous carbon hollow spheres as catalysts for CO2 hydrogenation to formate

Atomically dispersed Ru(III) catalysts on hierarchical and porous supports show great potential for application in the catalysis of the hydrogenation of CO2 to formate due to their high catalytic activity and stability. In this study, heterogeneous Ru(III) catalysts on N-doped mesoporous carbon hollow spheres (N-MCHS) were synthesized through a SiO2-templated resorcinol–formaldehyde polymer pyrolysis at different temperatures. At low pyrolysis temperatures (700–800 °C), the dominant N species on the catalysts were found to be pyrrolic and pyridinic N (Npyrrolic and Npyridinic). However, the dominant N species on the samples produced from 900 to 1000 °C was graphitic N (Ngraphitic). The highest catalytic activities on the batch hydrogenation experiments were recorded on the catalysts with the predominant Ru–Ngraphitic active sites. Using the Ru/N-MCHS-900 catalyst, the turn-over number (TON) was as high as 7550 after the hydrogenation for 2 h at 120 °C and 8 MPa. On the other hand, the Ru/N-MCHS-700 catalyst exhibited excellent stability in both batch and continuous reactors. No noticeable deactivation was observed even after 72 h of continuous hydrogenation, which can be attributed to the strong binding energy between the Ru(III) species, and the Npyridinic and Npyrrolic sites on the N-MCHS supports. This study provided significant insights for the development of novel heterogeneous catalyst systems for the hydrogenation of CO2 to formate.

A durable Ni/La-Y catalyst for efficient hydrogenation of γ-valerolactone into pentanoic biofuels

Zeolite-supported metal catalysts containing hydrogenation centers and acid sites are promising in the chemoselective hydrogenation of biomass platform molecules into value-added chemicals and fuels. The primary challenge of employing such bifunctional catalysts for biomass conversion lies in catalyst stability in the liquid phase under harsh conditions. Herein, we have prepared a Ni/La-Y nanocatalyst via an improved wet impregnation method. Compared with Ni nanoparticles on H-Y, La addition shows a significantly enhanced stability and performance in the continuous liquid-phase hydrogenation of γ-valerolactone (GVL) into ethyl pentanoate (EP) at 200 °C for 1000 h. Complementary characterization studies reveal that La addition in the metal/zeolite catalyst not only efficiently modulates the acid property of the zeolite to alleviate coke formation, but also suppresses zeolite dealumination and metal agglomeration and leaching upon catalysis over a 1000 h period. These findings provide an efficient approach for improving the stability of zeolite-supported bifunctional catalysts, leading to potential application in hydrogen-assisted biomass valorization under the liquid-phase conditions.

Continuous Catalytic Hydrogenation of a Key Intermediate of Riluzole Using a Micropacked-bed Reactor

Abstract A continuous selective catalysis of 4-(Trifluoromethoxy)aniline, a key intermediate in the preparation of riluzole, was studied using a micropacked-bed reactor (µPBR) packed with Pt/BAC catalysts. The effects of technological parameters such as solvent types, gas flow rates and liquid flow rates were investigated. It was indicated that the continuous hydrogenation process exhibited higher efficiency, selectivity and safety with less energy consumption compared to the traditional batch reduction process. The newly developed reactor system demonstrated a sustained and stable catalytic performance after 20 h running.

Solvent-free continuous flow hydrogenation of N-methylpyrrolidone to N-methylpyrrolidine catalyzed by bimetallic Pt/V on HAP

The continuous flow hydrogenation of N-methylpyrrolidone which catalyzed by Pt/V/HAP (Pt/V molar ratio = 1 : 0.5) was achieved running for 100 h with solvent-free, and the N-methylpyrrolidine yield was above 85.21%.

3D printed nickel catalytic static mixers made by corrosive chemical treatment for use in continuous flow hydrogenation

Catalytic static mixers, 3D printed from nickel alloys, were treated with etching or leaching solutions to activate their surfaces for use in hydrogenation of alkenes, aldehydes and nitro-groups.

Ultrastable Auto-Reduced Cu@C/Sio2 Catalyst Prepared Via a Sacrificial Coating Induced Encapsulation Strategy for the Continuous Hydrogenation of Co2-Derived Ethylene Carbonate

Ultrastable Auto-Reduced Cu@C/Sio2 Catalyst Prepared Via a Sacrificial Coating Induced Encapsulation Strategy for the Continuous Hydrogenation of Co2-Derived Ethylene Carbonate

Nickel Nanoparticles Embedded in Porous Carbon-Coated Honeycomb Ceramics: A Potential Monolithic Catalyst for Continuous Hydrogenation Reaction

Nickel Nanoparticles Embedded in Porous Carbon-Coated Honeycomb Ceramics: A Potential Monolithic Catalyst for Continuous Hydrogenation Reaction

Continuous hydrogenation of halogenated nitroaromatic compounds in a micropacked bed reactor

Continuous hydrogenation of halogenated nitroaromatic compounds in a micropacked bed reactor

Continuous and Selective Hydrogenation of Heterocyclic Nitroaromatics in a Micropacked Bed Reactor

The hydrogenation of heterocyclic nitroaromatics is of great importance in the pharmaceutical industry for the synthesis of key intermediates. However, high selectivity is difficult to achieve in c...

Continuous Hydrogenation: Triphasic System Optimization at Kilo Lab Scale Using a Slurry Solution

Despite their widespread use in the chemical industries, hydrogenation reactions remain challenging. Indeed, the nature of reagents and catalysts induce intrinsic safety challenges, in addition to demanding process development involving a 3-phase system. Here, to address common issues, we describe a successful process intensification study using a meso-scale flow reactor applied to a hydrogenation reaction of ethyl cinnamate at kilo lab scale with heterogeneous catalysis. This method relies on the continuous pumping of a catalyst slurry, delivering fresh catalyst through a structured flow reactor in a continuous fashion and a throughput up to 54.7 g/h, complete conversion and yields up to 99%. This article describes the screening of equipment, reactions conditions and uses statistical analysis methods (Monte Carlo/DoE) to improve the system further and to draw conclusions on the key influential parameters (temperature and residence time).

Continuous flow hydrogenation with Pd complexes of pyridine‐benzotriazole ligands

AbstractThe use of continuous flow systems in chemical synthesis provides great advantages in terms of sustainability, efficiency, and safety. The ability to control reaction parameters such as temperature, pressure, and catalyst exposure in flow system enables rapid optimization of reaction conditions. In the present study, palladium complexes of 1‐(piridin‐2‐il)‐1H‐benzo[d][1,2,3]triazol, N‐((1H‐benzo[d][1,2,3]triazol‐1‐il)metil)piridin‐2‐amin, and (1H‐benzo[d][1,2,3]triazol‐1‐yl)(pyridin‐2‐yl)methanone ligands were synthesized and characterized. The catalytic activities of complexes are investigated in the hydrogenation of various alkenes such as styrene, cyclohexene, and 1‐octene under continuous flow conditions. The complexes showed very high activity at 10‐bar H2 pressure and 50°C for short periods of 5–10 min. The catalysts reused for 10 cycles with no significant loss of catalytic activity.

POLITAG-Pd(0) catalyzed continuous flow hydrogenation of lignin-derived phenolic compounds using sodium formate as a safe H-source

• Tunable polymer support for Pd nanoparticles stabilization enhance the selectivity in phenols hydrogenation reaction. • Unprecedented selectivity in hydrogenation of different phenolic compounds using sodium formate as safe hydrogen-source under flow conditions. • Prolonged catalyst efficiency and selectivity up to 100 mmol of continuous phenols hydrogenation. Phenols are aromatic biobased compounds and as they are accessible from lignin depolymerization, they can be a useful platform chemicals to produce value-added products. Herein we report our recent investigations on the definition of an approach to the efficient continuous flow selective hydrogenation of phenols in water. Our protocol is based on the use of sodium formate as a clean and safe hydrogen source in combination with our newly defined heterogeneous POLITAG-Pd(0) catalytic system. POLITAG is a polymeric heterogeneous support decorated with pincer-type ionic ligands proven to be highly efficient for the stabilization of Pd(0) nanoparticles. The results obtained are remarkable in comparison with other protocols that employ sodium formate as H-source. Indeed, our investigation has been extended to a variety of differently substituted phenolic compounds that have been hydrogenated with excellent to good selectivity in continuous flow conditions. Durability of the catalyst has been also tested with a representative continuous processing of over 100 mmol that showed no loss in efficiency and minimal metal leaching.

Continuous hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol at Cu-MoOx interface with a low H2/ester ratio

The Cu-based catalysts have been widely employed in the hydrogenation of CO2-derived ethylene carbonate (EC) to methanol (MeOH) and ethylene glycol (EG), but still suffered from some problems such as excess hydrogen/ester ratio, unsatisfactory MeOH selectivity and catalyst stability & deactivation. Herein, a MoOx-promoted Cu/SiO2 catalyst, which was prepared via a one-pot modified hydrothermal method and derived from copper phyllosilicate precursors, exhibited superior catalytic performance (89% MeOH yield and 99% EG yield) and good stability (>150 h) at a H2/EC ratio (20). Remarkably, the turnover frequency (TOF) and space time yield of MeOH (STYMeOH) reached up to 17.5 h−1 and 0.207 g⋅gcat−1⋅h−1, respectively, which are among the highest values in the literature data. The characterization results and kinetic studies revealed that modification of Cu species by MoOx obviously changed the electronic properties of Cu species, reduced the activation energy and enhanced the Cu+/(Cu0 + Cu+) ratios. Such modification may lead to possible formation of Cu-O-Mo bond between Cu species and MoOx species located on the periphery of Cu-MoOx interface, which might strengthen the adsorption and activation of EC, stabilize the Cu nanoparticles, and thus improve the selectivity to MeOH and catalyst stability. In addition, MoOx decoration had obvious effect on the strength and quantity of the surface acid sites.

Cellulose-based catalyst design for efficient chlorate reduction

The reduction of undesirable chlorate (ClO3-) is important from both an environmental and an industrial point of view. In our work, cellulose-based catalysts have been designed for chlorate reduction by using palladium, platinum, and iron oxide. The produced catalysts were characterized by SEM, TEM, XRD, FTIR, and ICP. Even though low precious metal content (<0.6 wt%) was used during the catalyst preparation, high catalytic activity was achieved, and the conversion was as high as 92.5%. Furthermore, a continuous chlorate hydrogenation and monitoring system has also been developed within which the reduction has been carried out successfully and after about 160 min the ClO3- content has been reduced to zero.