Narendra Kumar

Åbo Akademi University · Faculty of Science and Engineering, Industrial Chemistry and Reaction Engineering

The Special Issue “Microporous and Mesoporous Materials for Catalytic Applications has twelve peer-reviewed articles (Contributions 1–12), out of which there are eight research papers (Contributions 1–8) and four review papers (Contributions 9–12) [...]

Oral presentation at Ibero-American Catalysis Congress (XXIX CICAT 2024) held on Bilbao-Spain (23-27 sep).

The Special Issue “Exclusive Papers of the Editorial Board Members and Topical Advisory Panel Members of Catalysts in Section “Catalytic Materials” contains 14 peer-reviewed research articles and 1 review paper (Contributions 1–15), which broadly focus on the field of homogeneous and heterogeneous catalysis, with an emphasis on synthesis, physico-c...

Several parents and Sn-modified microporous and mesoporous catalysts were investigated in Prins cyclization of isoprenol with isovaleraldehyde for the production of the desired cis isomer of pyranol, Florol ® using dimethylcarbonate as a solvent in the temperature range of 30–60 ◦C. The highest selectivity to pyranols, 70% was obtained over micropo...

Parent, hierarchical, and metal-modified hierarchical zeolite Y were investigated as heterogeneous catalysts in the R-(+)-limonene epoxidation, a catalytic route for synthesizing precursors of bio-polycarbonates, an alternative to isocyanate polyurethanes. The fresh catalysts underwent detailed characterization using XRD, N2 physisorption, TEM, SEM...

Furfural is a very interesting bio-based platform molecule that can be derived from the pentoses found in hemicelluloses, such as xylose and arabinose. Furfural has shown a significant potential as...

Hydrodeoxygenation (HDO) of isoeugenol was carried out at 200 °C and 30 bar of H2 in a batch reactor using a series of bifunctional catalysts consisting of platinum supported on zeolite H-Beta-25 or H-Beta-300 and Bindzil as a binder. The purpose of the matrix was to understand the effect of the binder on the reaction, emulating the components of i...

Titanium silicates of MWW structures with different Si/Ti ratios were prepared via hydrothermal synthesis using piperidine as the structure directing agent and boric acid as the crystallization agent. All the syntheses resulted in highly crystalline materials independent of the Si/Ti ratio. The observed morphology showed MWW-like well-defined thin...

Electrocatalytic conversion of hemicellulose-derived glucose and xylose presents a sustainable approach to utilize renewable energy (e.g. solar, wind) to produce value-added chemicals. In this work, the electrochemical hydrogenation and oxidation of glucose and xylose at ambient conditions were studied using dispersed, mesoporous Sibunit Carbon (SC...

Although catalyst shaping by extrusion has been industrially applied for decades to suppress the pressure drop, much less emphasis was put on fundamental understanding of extrusion for catalytic pastes and its effect on the properties of the final catalyst bodies. During recent years intensive research efforts have been put on synthesis of extrudat...

Methyl levulinate was selectively formed from glucose and methanol over a copper modified Beta zeolite bifunctional catalyst at 180 °C under argon atmosphere. The selectivity to methyl levulinate substantially exceeded previously reported in the open literature results. The copper modification was done through an ion-exchange method using a solutio...

Recent evidences have shown catalyst structure sensitivity of electrocatalytic hydrogenation (ECH) of organic molecules in aqueous phase. In this study, ECH of glucose and xylose was investigated using gold nanoparticles (AuNPs) on activated carbon fiber (CF) support as catalyst. CF supported AuNPs catalysts (CF/AuNPs) were synthesized by depositio...

Mesoporous materials are promising catalysts for production of biofuels. Herein, H-MCM-41 catalysts with different concentrations of the silica Bindzil binder (10-50 wt%) were prepared and characterized using pulsed-field gradient (PFG) NMR in the powder form and as extrudates. Effective diffusion coefficients (De) are measured in all cases. Diffus...

In this work, the formation of levulinic acid (LA) as one of the top-twelve chemical building blocks from glucose was studied. In particular, the formulations of heterogeneous acid catalysts based on SBA-15, MCM-41 mesoporous silica was carried out and their performance in catalytic conversion of glucose to LA were assessed and compared with commer...

Cyclic carbonates are important platform molecules with relevant industrial applications such as polymers precursors, fuel additives and solvents. They can be obtained from epoxidized vegetable oils via a carbonation reaction with carbon dioxide. This process is typically performed using homogenous catalyst or co-catalyzed systems, requiring of a h...

In this work, several heterogeneous micro- and mesoporous, acidic catalysts were tested for the selective synthesis of Florol®, an industrial product formed via condensation and rehydration starting from isoprenol and isovaleraldehyde in dimethylcarbonate as a solvent. The results showed that a mildly acidic, microporous H-Beta-300 with SiO2/Al2O3...

Four clay materials, namely, bentonite, bleaching earth, attapulgite and sepiolite, were shaped into the cylindrical body by extrusion. Clays were characterized in depth by TEM, SEM-EDX, N2 physisorption, pyridine FTIR, pH measurements, contact angle measurements, ²⁷Al MAS NMR, and the crush test. Catalytic properties were investigated in the citro...

A series of monometallic platinum and bimetallic platinum–rhenium catalysts supported on mesoporous carbon Sibunit, which is a type of mesoporous, microcrystalline carbon, were investigated for hydrodeoxygenation (HDO) of isoeugenol (IE) at 200–300 °C and 30 bar of H2, using dodecane as a solvent. Catalytic activity was tested in a batch reactor to...

The present work is focused on the improvement of an effective approach to tailor the acidity of silica alumina composite. SBA-15 was selected based on high surface area, uniform porosity and large mesopores. Modification of SBA-15 was performed to improve both Lewis and Brønsted acidities and hence catalyst activity. Therefore, introduction of alu...

One-pot transformations of citral were investigated over Ru-catalysts in a batch and a continuous mode over a powder catalyst and extrudates, respectively. Ru/H-Y-80 catalysts were prepared by different impregnation methods to obtain different particle sizes of Ru. The highest yield of isopulegols was 15% and yield of menthols was 3% with stereosel...

The carboxymethylation of cinnamylalcohol with dimethyl carbonate was performed using low-cost catalysts obtained from desulfurization slag. Processing of steel slag performed by different techniques was resulted in a wide range of the catalysts with different morphological and structural properties. Catalytic evaluation of the slag catalysts illus...

Ibuprofen (IBU) and diclofenac (DCF) are non-steroidal anti-inflammatory pharmaceuticals. They are frequently detected in wastewater and in the environment. Due to their harmful effect on aquatic organisms, new methods should be developed to enhance their removal from wastewater. One efficient wastewater treatment process is ozonation. In this stud...

Microporous zeolites and related nanoporous materials have been studied intensively in academic and industrial laboratories around the world [...]

Catalytic dimerization of 1‐hexadecene is shown to be a promising path to make high quality base oil. The base oil is produced by hexadecene dimerization with acid mesoporous silica‐alumina catalyst, followed by distillation and hydrogenation. The base oil stock had a high viscosity index (typically 140–150) and a low volatility (Noack typically le...

The three steps reaction of citral to menthol was investigated in an autoclave and a trickle-bed reactor over Ru-MCM-41 catalyst in a powder and shaped forms, respectively, with the same composition, and controlled metal location. All catalysts were characterized in detail and the results were correlated with catalytic tests. Activity and selectivi...

BACKGROUND The metal–acid bifunctional catalysts are widely used in many industrially significant chemical processes, including hydroisomerization of n‐hexane. Deactivation and regeneration of metal–acid bifunctional extrudates was investigated in continuous n‐hexane hydroisomerization in a fixed‐bed reactor. Four Pt/H‐Beta‐25 catalysts containing...

Waste minimization strategy was applied in the current work for synthesis of the catalysts from industrial solid waste, namely desulfurization slag. The starting slag material comprising CaCO3, Ca(OH)2, SiO2, Al2O3, Fe2O3, and TiO2 was processed by various treating agents systematically varying the synthesis parameters. A novel efficient technique...

Sub-nanometer zeolite 13X-supported Ni-ceria catalysts were synthesized for CO2 methanation. XRD and SEM results show the structure and morphology of 13X zeolite after impregnation and calcination. Ce loading affected the catalysts’ metal dispersion, reducibility, basicity and acidity, and thence their activity and selectivity. STEM-EDX elemental m...

Transformations of glucose to 1,2-propylene glycol were studied over a mechanical mixture of ZnO and Ru/C catalysts in the presence of hydrogen. Different reaction conditions were evaluated by changing the reaction temperature and hydrogen pressure. In addition to the cascade mode of operation, also separate steps in the overall reaction network, s...

Cascade transformations of (±)-citronellal in a continuous mode were investigated over a bifunctional shaped ruthenium catalyst bearing metal clusters of the size 7–13 nm. Four types of Ru/H-MCM-41 extrudates (1.5 × 10 mm) containing 30% of Bindzil-50/80 colloidal silica binder were prepared varying in metal location and metal-to-acid ratio, while...

Hexadecane hydrocracking was investigated over bifunctional Ru-containing micro- and mesoporous USY zeolites at 250°C under 45 bar in the presence of hydrogen in a batch reactor. A comparative study was performed using the Ru-free zeolites in the protonic form. The highest yield of jet-fuel products, C9 - C15, being 26% at 71% conversion, was obtai...

Zeolites 13X and 5A were modified with nickel and/or ruthenium for CO2 methanation. The catalysts were prepared by evaporation impregnation and XRD, SEM-EDX, TEM, STEM-EDX, nitrogen physisorption, H2-TPR and NH3-TPD were used to characterize the physico-chemical properties of the catalysts. The physico-chemical characterization results show that th...

Heterogeneous catalysts are widely used in the chemical industry. Compared with homogeneous catalysts, they can be easily separated from the reaction mixture. To design and optimize an efficient and safe chemical process one needs to calculate the energy balance, implying the need for knowledge of the catalyst’s specific heat capacity. Such values...

Dehydration and etherification of bio-ethanol was studied in a microreactor using γ-alumina, H-Beta-38 and Sn-Beta-38 as catalysts. An extensive series of kinetic experiments was carried out in the microreactor device operating at ambient pressure and temperatures 225-325°C. The H-Beta-38 catalyst coated microplates exhibited the highest production...

The presence of pharmaceuticals in surface water, drinking water, and wastewater has attracted significant concern because of the non-biodegradability, resistance, and toxicity of pharmaceutical compounds. The catalytic ozonation of an anti-inflammatory pharmaceutical, ibuprofen was investigated in this work. The reaction mixture was analyzed and m...

Carbamazepine (CBZ) is a recalcitrant pharmaceutical often detected in wastewater and in the environment. CBZ can be removed from wastewater through advanced oxidation treatment methods such as ozonation. In this study, CBZ and its transformation product 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) were ozonated, and the formation and tra...

Zeolite 13X and 5A supported Ni catalysts were synthesized for CO2 methanation using the evaporation impregnation method. The influence of using different Ni precursors (nitrate, citrate, and acetate) as well as calcination temperatures on the catalyst properties and performance were investigated. XRD, SEM-EDX, TEM, STEM-EDX, N2 physisorption, H2-T...

The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-1...

Synthesis of Beta zeolite catalysts was carried out using two different methods. The influence of such parameters as synthesis time and temperature, gel composition and gel ripening on the physico-chemical and catalytic properties of Beta zeolite catalysts was studied. A range of analytical methods was applied in this work including scanning and tr...

The degradation of the pharmaceutical compound diclofenac in an aqueous solution was studied with an advanced oxidation method, catalytic ozonation. Diclofenac was destroyed in a few minutes by ozonation but several long-lasting degradation by-products were formed. For this reason, the combination of heterogeneous catalysts and ozonation was applie...

Carbamazepine (CBZ), a widely used pharmaceutical compound, is one of the most detected drugs in surface waters. The purpose of this work was to identify an active and durable catalyst, which, in combination with an ozonation process, could be used to remove CBZ and its degradation products. It was found that the CBZ was completely transformed afte...

One-pot menthol synthesis from citronellal in a trickle bed reactor was investigated using Ru/H-Beta-300 zeolite extrudates without any binder and Pt- and Ru-extrudates containing 70 wt% H-Beta-25 zeolites and 30 wt% bentonite binder using different methods of metal loading on the extrudates. The catalytic results were correlated with the physico-c...

Hydrocracking of hexadecane to produce jet fuel components was investigated over proton and metal modified Beta zeolites with different acidity. They were characterized by a range of physico-chemical methods. The initial catalyst screening was performed at 210 °C under 40 bar hydrogen showing that the most promising catalysts were 2.5 wt% Pt-H-Beta...

Citronellal cyclization was carried out in a continuous mode over H-Beta-25 zeolite-based extrudates in a trickle-bed reactor at 35 °C and 10 bar of Ar. The physico-chemical properties of zeolitic catalysts in the form of extrudates with a different diameter (1.4 – 3 mm) containing 30 wt.% of a binder were correlated with the catalytic results. Alu...

Background In the production of biofuels from lignocellulosic material, biocrude plays a key role. The present work deals with the biocrude production through hydrothermal liquefaction (HTL) of birch wood in supercritical ethanol over 5 wt% Fe‐H‐Beta‐150 (SiO2 to Al2O3 ratio of 150) or 5 wt% Fe‐SiO2 catalyst. Results The liquid and solid products...

Continuous cyclization of citronellal over zeolite-based extrudates was performed in a trickle-bed reactor at 35 – 70 °C and 10 bar of argon. Catalytic results were correlated with the physico-chemical properties of the shaped catalyst prepared by extrusion of Beta or Y zeolites with binders. Rheological tests were used to elucidate the flow proper...

Industrial ferrous wastes found their application in construction. However, they are mostly stored polluting the environment. In the current work, possibility of value added products synthesis from steel slag with their further use as catalysts was investigated. Slag-based catalysts were obtained by alkaline treatment with sodium hydroxide by varia...

A straightforward and reliable method was successfully developed for stainless steel microreactor coating. The importance ofthiscoatingmethodliesinusinganalreadypre-preparedAu/Al2O3 catalystwithoutincorporation of any binders, addressing the importance of the interplay between the catalyst particle size and slurry viscosity in optimization of the u...

Four different types of shaped catalysts with controlled deposition of platinum and the same composition were prepared by extrusion from Beta zeolite agglomerated with bentonite as an aluminosilicate clay binder. The catalysts were characterized using mechanical strength tests, scanning electron microscopy for morphology, transmission electron micr...

Nanoparticles exhibit a range of different properties when compared to bulk materials. Their high surface-area to volume ratio makes them particularly attractive for use as catalysts and recent years have seen an explosion of research in this area. The ability to fine-tune the size and structure of nanoparticles means that it is possible to design...

Kinetics of the cross aldol condensation of valeraldehyde with cyclopentanone was investigated in a batch reactor under atmospheric pressure at 130 °C using heterogeneous metal modified oxides, such as CeO2–MgO, FeO–MgO, FeO–CaO as well as pristine CaO as catalysts. The catalysts were prepared either by evaporation impregnation or deposition precip...

Oxychlorination of ethene was conducted in a microreactor (150–375 °C) over a thin layer of CeO2 prepared in the current work with the specific surface area of 80 m2/g and compared with the same reaction in millireactors (250–500 °C). The kinetic analysis revealed influence of the ethene concentration on the apparent activation energy which was dif...

Industrial slag containing Si, Al, Ca, Fe, Mg and Ti was used as source for synthesis of novel catalytic materials upon variation of the treating agents (sodium hydroxide, ethylenediaminetetraacetic acid disodium salt dihydrate - sodium hydroxide and tetraethylammonium hydroxide - sodium hydroxide mixtures) and synthesis parameters (solution concen...

Activity of heterogeneous catalysts for synthesis of Guerbet alcohols from hexanol was evaluated. Commercial synthetic hydrotalcite (HT) was used in the aldol condensation reaction, which is a part of the Guerbet reaction network. HTs were calcined at different temperatures in order to modify their basicity and additionally, NaOH was applied in som...

Synthesis of materials with combined chemistry and textural properties of carbon and silica aerogels was studied. The synthesized support was modified with ruthenium using evaporation impregnation and deposition–precipitation methods. The ruthenium modification methods were observed to influence the particle size, dispersion, surface area, pore vol...

Composite materials for shaped catalysts were prepared from three commercial Beta zeolites using bentonite as an aluminosilicate clay binder. All pristine materials and the synthesized powder mixtures were characterized using X-ray powder diffraction for phase purity and structure, scanning electron microscopy for morphology, transmission electron...

Silver modified (5 and 2 wt% loading) mesoporous molecular sieves (H-MCM-41, with Si/Al ratio 20, 40 and 50) and silica were synthesized by incipient wetness impregnation and ion-exchange methods. The obtained catalysts were characterized by different techniques (ICP, XRD, XRF, SEM, FTIR and nitrogen physisorption) and they were tested in heterogen...

During olive oil extraction, large amounts of phenolics are generated in the corresponding wastewaters (up to 10 g dm–3). This makes olive oil mill wastewater toxic and conventional biological treatment challenging. The catalytic wet peroxide oxidation process can reduce toxicity without significant energy consumption. Hydrogen peroxide oxidation o...

Oxychlorination of ethene was performed over CuCl2/γ-Al2O3 catalyst in a microreactor (460 µm in diameter) and for comparison in a millireactor (1 cm in diameter). A copper-modified catalyst was prepared by a conventional evaporation–impregnation method without any promotors (e.g., K, Na, La) using copper (II) chloride as a precursor. The catalyst...

Hydrodeoxygenation of isoeugenol was investigated at 200°C under 30 bar total pressure in dodecane as a solvent in hydrogen over bifunctional Pt‐ and Ir‐modified beta zeolites and mesoporous materials. As a comparison, also Pt‐ and Ir‐supported on Al2O3, SiO2 and mesoporous MCM‐41 were tested. The catalysts were characterized by XRD, CO pulse chemi...

Measurements of the zeta potential of solid heterogeneous supports are important for preparation of metal supported catalysts and for shaping zeolites into extrudates. In the current work, different types of heterogeneous support materials such as SiO₂, Al₂O₃, and a range of beta zeolites of different silica- to-alumina ratio were analysed. It was...

Five different support materials were modified with 5 wt.% Cu, using an evaporation impregnation method. The synthesized CuCl2/γ-Al2O3, CuCl2/TiO2 (Hombikat), CuCl2/TiO2 (Alfa Aesar), CuCl2/SiO2 and CuCl2/H-Beta-25 materials were characterized by nitrogen physisorption, X-ray powder diffraction, scanning electron microscopy, energy dispersive Xray...

Direct amination of 1-dodecanol with NH3 and H2 over Rh, Pt, Ir, Ru, Ni, Cu and Co catalysts on SiO2 has been studied. Catalyst synthesis was performed to allow high metal dispersion. The catalysts were characterized by TPO / TPR-MS, N2 physisorption at 77 K, Transmission Electron Microscopy, ICP Analysis and XPS. Through this characterization it w...