Miha Grilc

National Institute of Chemistry · Department of Catalysis and Chemical Reaction Engineering

The origins of GA date back to the 1880s, when it was first produced by Kiliani by oxidising D-glucose with nitric acid. Since then, scientists have explored alternative manufacturing processes, which we discuss here. The utility of GA is an excellent incentive for developing an industrially applicable, environmentally friendly manufacturing proces...

Rhenium is a versatile element and increasingly used in solid catalysts for the conversion of biomass, where it can fulfill different roles in providing or improving catalytic activity. On the other hand, this also makes Re-based catalysts susceptible to various types of catalyst deactivation. Deactivation mechanisms, detection methods, and coping...

Benzyl phenyl ether (BPE) was used as a model compound to study the mechanism of the α-O-4 bond cleavage in lignin. The selection of solvent (methanol, ethanol, γ-valerolactone, water), catalyst loading (0.5 – 1.5 wt% of H2SO4) and the effect of the reaction temperature (160 – 200 °C) on the acidolysis, performed in a batch reactor under an inert a...

Deoxygenation of triglycerides is one of the crucial pathways for the production of oxygen-free hydrocarbons and biofuels that are fully compatible with conventional internal combustion engines. The one-step liquefaction and hydrotreatment of Chlorella sorokiniana microalgae was investigated in a three-phase slurry reactor. The production of diesel...

Two lignin model compounds, eugenol (Eu) or 2-methoxy-4-propylphenol (MPP), were esterified with a protonating acetic acid (AcA), H2SO4 catalyst and water. Initial product analysis showed a high related number of the unspecific process species of Eu reactions. Therefore, research was continued only with MPP. Temperature, equivalent MPP/AA molar rat...

As the most abundant C1 carbon source, as well as renewable and highly environmentally unfriendly compound, carbon dioxide serves as a very promising compound for the chemical industry. This review focuses on heterogeneous catalytic conversion of CO2 to various compounds, which would then offer reusable, cheaper, and safer reaction conditions. Most...

In this study, an acidic deep eutectic solvent (DES) was used as benign solvent to valorise technical lignins by breaking down their structure into value-added aromatic compounds. The action of an acidic DES composed of cholinium chloride ([Ch]Cl) and oxalic acid (Oxa), at molar ratio 1:1, towards depolymerisation of Kraft and Organosolv lignins (K...

Over the last few years, there has been an impetuous search for natural colorant to be applied in various industries, such as cosmetics, food, and textile. This is largely driven by an increasing consumer demand for formulated ingredient products that are not only considered safer than their synthetic counterparts, but also present medicinal health...

The development of the novel analytical methodologies for lignin chracterisation is presented. Lignin fractions were characterized by NMR, SEC/GPC as well new analytical methodologies were implemented such as FT–IR, UV and fluorescence. FT–IR and fluorescence results show a promising correlation to the NMR and SEC/GPC analysis. Main findings from t...

The heterogeneously catalyzed dehydroxylation of mucic acid to produce adipic acid, a highly relevant polymer precursor, was investigated. The use of methanol as solvent is particularly important since it not only acts as reducing agent but also protects the carboxylic acid functionality by esterification. Re/C was found a well-suited catalyst for...

Microalgae have emerged as a promising feedstock for third generation biofuels. This study aims to investigate the reaction conditions for biodiesel production from microalgae. Microalgae were liquefied and transformed into a mixture of diesel like hydrocarbons using commercial bifunctional NiMo/γ-Al2O3 catalyst. GC-MS analysis revealed that the pr...

Hydrogenation, hydrodeoxygenation and ring opening of biomass-derived furfural were studied by using Pd/C, Pt/C, Re/C, Ru/C, Rh/C, Ni/C and Cu/C catalysts. Based on experiments, a generalized micro-kinetic model was developed, describing kinetics of tested catalysts well. Pd/C could unselectively hydrogenate furfural’s ring, aldehyde group or both...

Plastic waste is steadily polluting oceans and environments. Even if collected, most waste is still predominantly incinerated for energy recovery at the cost of CO2. Chemical recycling can contribute to the transition towards a circular economy with pyrolysis combined with steam cracking being the favored recycling option for the time being. Howeve...

The lignin-to-chemicals valorisation has increased the interest of the scientific community in exploring the effective lignin depolymerisation. Lignin is the most abundant natural resource of aromatic components with a high potential to be converted into the various chemicals, thus increasing the level of an integrated biorefinery. This review focu...

Seven fast-growing invasive plant species were harvested in Slovenia and tested for their valorisation potential in the pulp and paper industry with the aim of sustainable substitution of commercial cellulose fibres. Cellulose fiber materials were isolated by filtration after solubilizing extractives, lignin and hemicellulose in a kraft pulping pro...

Article offers a review of the mechanisms, kinetics and effects of the analysed process conditions on the conversion, selectivity and catalyst chemical stability of the hydrogenation, hydrocracking and hydro-deoxygenation (HDO) transformation reactions of biomass-derived fatty acids. Sequences discussed include all functional steps from the hydroge...

Growing challenges with climate change and pollution caused by the use of fossil fuels triggered the utilization renewable energy sources where biomass has gained a great deal of attention because of its abundance and availability. Biomass valorisation includes various (de)functionalisation processes, that strongly rely on hydro(deoxy)genation, and...

The magnetically heated hydrotreatment of levulinic acid, furfural and hydroxymethylfurfural over a composite Ru-based nanocatalyst in a batch reactor was investigated. The nanocatalyst's dual role as a heating agent and catalytically active material was demonstrated. The in-depth analysis and modelling of the hydrogenation and deoxygenation proces...

Carboxylation reactions using carbon dioxide (CO2) as a reactant to produce new C-C bonds, represent one of the most promising routes in carbon capture and utilization practices, which yield higher atom and energy efficient products. Kolbe-Schmitt-type reactions represent carboxylation of aromatic compounds to their carboxylic acid derivatives. Thi...

Dehydration of the most relevant biomass derived monosaccharides, xylose, glucose and fructose, was investigated to attain value-added platform chemicals: furfural, hydroxymethylfurfural (5-HMF) and levulinic acid (LA).

The aim of the study was to isolate lignin from organosolv, beech tree (Fagus sylvatica), and Japanese knotweed (Reynoutria japonica), to use it for paper surface and to replace part of the non-renewable product resources with bio-based ones. A total of nine coated samples with different lignin formulations and starch were compounded, prepared, and...

Six enzymes were tested against HMF and its oxidation intermediates to determine substrate specificity, product yield and pathways. A Michaelis–Menten kinetic mathematical model was constructed and some rate parameters calculated. The best 2,5-diformylfuran (DFF) productivity was obtained with alcohol oxidase (AO) and 10.0 mM HMF, where 3.0 mM DFF...

The limited reserves and well-known disadvantages of using fossil energy sources have increased the need for appropriate renewable substitutes in the production of various chemicals and materials. Biomass has been shown to be worthy of attention since it can be converted to biofuels and value-added chemicals relatively easily. The design of biomass...

In recent years, flavonoids have become a highly researched topic due to their health beneficial effects. Since flavonoids’ solubility plays a significant role in their use in pharmaceutical, food, biological, and chemical areas, the determination of suitable solvents is crucial. Fourier transform infrared (FTIR) analysis was used to characterize f...

The related immense versatility of a ceria-promoted transition metal catalyst, utilized for the hydrogenation of 5-hydroxymethylfurfural (HMF), is demonstrated in this research study. We reveal a capability to achieve a...

Machine learning through artificial neural networks have emerged as vital tools to predict chemical behavior for many of the most recognized biomass valorization processes relevant to biorefineries for the purpose of optimization of desired products and reaction conditions. Until recently, these neural network methodologies have successfully been u...

5-hydroxymethylfurfural (5-HMF) and furfural (FUR) have been recognized as valuable biomass-derived platform chemicals and bridge between biomass raw materials and the biorefinery industry, utilizing as a building blocks for the production of many chemicals and fuels. In this review, we aim to discuss the utilization of process intensification (PI)...

Plastics floating in ocean gyres are a popular topic within pollution discussion; however, no simple solution exists to deal with marine litter. Overcoming limitations in collection, and perhaps even more in the environmentally, technically and economically acceptable use of the collected material, is of paramount importance. This paper presents in...

Comparative studies over micro-/mesoporous Cu-containing zeolites ZSM-5 prepared by top-down treatment involving NaOH, TPAOH or mixture of NaOH/TPAOH (tetrapropylammonium hydroxide) were conducted. The results of the catalytic data revealed the highest activity of the Cu-ZSM-5 catalyst both in the absence and presence of water vapor. The physico-ch...

Lignin is a wasted renewable source of biomass-derived value-added chemicals. However, due to its material resistance to degradation, it remains highly underutilized. In order to develop new, catalysed and more environment friendly reaction processes for lignin valorization, science has turned a selective concentrated attention to microbial enzymes...

Raising the awareness of carbon dioxide emissions, climate global warming and fossil fuel depletion has renewed the transition towards a circular economy approach, starting by addressing active bio-economic precepts that all portion amounts of wood are valorised as products. This is accomplished by minimizing residues formed (preferably no waste ma...

Over the last years, the depletion of fossil resources allied with the growing energy demands and the increasing environmental pollution turned imperative the search for alternative renewable resources. Lignocellulosic biomass has been recognized as an excellent alternative feedstock due to its availability, renewability and low cost. Lignin, one o...

In the last decade, much of the research was focused towards bio refining, mainly due to increased greenhouse gases arising from the use of the non-renewable resources. Since biomass contains more oxygen than hydrocarbons, catalytic hydrogenation and/or hydro-deoxygenation may be used to remove oxygen from derived bio-oils to improve their stabilit...

Bio-based levulinic acid (LA), furfural (FF), and hydroxymethylfurfural (HMF) represent key chemical intermediates when biorefining biomass resources, i.e., either cellulose, glucose, hexoses, etc. (HMF/LA), or hemicellulose, xylose, and pentose (FF). Despite their importance, their online in situ detection by process analytical technologies (PATs)...

Biomass conversion into fuels and added-value chemicals, in high yield and with good selectivity, is still a great issue and an attractive research topic. The design and the optimization of defunctionalisation processes require accurate kinetic models that take into account the solubility of various gases in the bio-based chemicals present in the p...

Valorization of lignocellulosic biomass, particularly catalytic hydrotreatment of hemicellulose-based furfural (FUR), has been studied for the production of value-added chemicals. A three-phase batch reactor has been used for hydrotreatment in isopropanol over various commercially available unsupported MoOx catalysts, at various temperatures (170–2...

In this study, acidolysis of benzyl phenyl ether (BPE), being a representative lignin model compound with the α-O-4 linkage, was examined in γ-valerolactone (GVL) and a GVL/water mixture, each time acidified with sulfuric acid. The product distribution was strongly affected by water used as a cosolvent, which was found to be advantageous by inhibit...

In the present work, the conversion of bio‐based aldaric acids into muconic and adipic acid through a heterogeneous catalytic process, in the absence of corrosive reagents or gaseous H2 is reported. The mechanism of the selective removal of adjacent OH* groups on Re/C catalysts and the role of (m)ethanol in carboxylic group protection and hydrogen...

Extensive experimental and computational study of hemicellulose-derived furfural hydrogenation, hydrodeoxygenation, oligomerisation and etherification has been conducted over Pd/C catalyst. In-situ reduction of PdO surfaces was observed, forming predominately Pd(1 1 1). Tetrahydrofurfuryl alcohol was observed as the main product. Selected solvent (...

Catalytic hydrodeoxygenation of hydroxymethylfurfural was investigated in a three-phase batch reactor over a range of reaction temperatures (170–230 °C), under 5 MPa of hydrogen, and tetrahydrofuran solvent. Nickel-based carbon-supported catalysts were also promoted by lanthanum and niobium, despite promoters alone demonstrated no activity. Based o...

Being one of the most demanded dicarboxylic acids, adipic acid can be directly produced from renewable sources. Hexoses from (hemi)cellulose are oxidized to aldaric acids and subsequently catalytically dehydroxylated. Hitherto performed homogeneously, we present the first heterogeneous catalytic process for converting an aldaric acid into muconic a...

Conventional biorefinery processes are complex, engineered and energy-intensive, where biomass fractionation, a key functional step for the production of biomass-derived chemical substances, demands industrial organic solvents and harsh, environmentally harmful reaction conditions. There is a timely, clear and unmet economic need for a systematic,...

Ruthenium catalyzed and magnetically heated hydrogenation of furfural in a slurry-type reactor is demonstrated in this work. We have developed a catalyst composed of magnetic-nanoparticles-containing alumina carrying Ru nanoparticles on...

The selective lignin conversion into bio-based organic mono-aromatics is a major general challenge due to complex structure itself/additional macromolecule modifications, caused by the cleavage of the ether chemical bonds during the lignocellulosic biomass organosolv pulping in acidified aqueous ethanol. Herein, the acido-lysis of connected benzyl...

Plastics industry technologies currently source the majority of monomers from crude oil substances. Although we have witnessed a significant companies’ interest towards the utilization of the sustainable feedstock materials for the bio-based compound synthesis in a the past decade, the transition to the photosynthetic or chemosynthetic plant-based...

Utilization of magnetic nanoparticle-mediated conversion of electromagnetic energy into heat is gaining attention in catalysis as a source of heat needed for a substrate’s chemical reaction (electrification of chemical conversions). We demonstrate that rapid and selective heating of magnetic nanoparticles opens a way to the rapid synthesis of a nan...

A bottom-up approach was formulated and used as a strategy in our work to systematically investigate the removal of lignin functionalities and the hydrogenolysis of the typical bonds relevant for lignin. In the previous studies, the role of metals and supports of 16 commercial catalysts (Pt, Pd, Rh, Ru, Ni, Cu supported on C, Al2O3, SiO2, SiO2-Al2O...

Background 2,5-Furandicarboxylic acid (FDCA) is one of the top biomass-derived value-added chemicals. It can be produced from fructose and other C6 sugars via formation of 5-hydroxymethilfurfural (HMF) intermediate. Most of the chemical methods for FDCA production require harsh conditions, thus as an environmentally friendly alternative, an enzyma...

Methane is the central component of natural gas, which is globally one of the most abundant feedstocks. Due to its strong C–H bond, methane activation is difficult, and its conversion into value-added chemicals and fuels has therefore been the pot of gold in the industry and academia for many years. Industrially, halogenation of methane is one of t...

The hydrodeoxygenation (HDO) reaction kinetics of lignin monomer model compound eugenol was systematically investigated over various commercially available catalysts typically used for lignin valorisation by hydrotreatment. The role of noble metals Pt, Pd, Rh, Ru, and non-noble Ni and Cu on C was investigated in the previous studies, while the pres...

The development of high-performance bio-based copolymers such as poly(styrene-co-butyl acrylate-co-methacrylic acid) for paints and coating applications is indispensable to the establishment of a sustainable green society, but it is challenging due to the incompatibility of their syntheses of methacrylic acid (MAA) from biomass. The decarboxylation...

An environmentally-benign, efficient and inexpensive high-surface-area barium hexa-aluminate (BaAl12O19, BHA) was developed as a catalyst for the decarboxylation of the biomass-derived itaconic acid (IA) to bio-based methacrylic acid (MAA). A maximal 50% final yield of MAA with a high product selectivity was obtained under relatively mild synthesis...

Methacrylic acid (MAA) is a polymer molecular constituent in related plastics industry, presently produced from supplied fossil-based resources. This scientific paper reports an environmentally-benign catalytic process for the production of MAA via the decarboxylation of carboxylic groups. Various hexaaluminate catalysts were synthetized examined a...

Ethylene epoxidation is one of the most important selective chemical oxidations in industry. For a controlled transformation of ethylene (ethene) into epoxide, silver is the only commercially suitable catalyst. Although it is usually doped, even with pristine silver activity, selectivity, and stability vary strongly with facets. In this work, we us...

The gasification of biomass is one of the most prominent technologies for the conversion of the raw material feedstock to polymers, useful chemical substances, and energy. The main engineering challenge during the processing of wastes is the presence of tars in gaseous reaction products, which could make this operation methodology unsuccessfully du...

Numerous research studies have recently demonstrated a huge physical potential of the cascade companies’ utilization of the renewable waste ligno-cellulosic biomass sources by the fractionation, de-polymerization and valorization of cellulose, hemicellulose, and lignin, separation, and subsequent catalytic conversion of the monomeric building block...

Hydrotreatment of mucic acid (also known as galactaric acid, an glucaric acid enantiomer), one of the most promising bio-based platform chemicals, was systematically investigated in aqueous media over alumina, silica, or carbon-supported transition (nickel and nickel-molybdenum) or noble (platinum, ruthenium and rhodium) metals. Mucic acid was only...

Deep eutectic solvents (DES), prepared from choline chloride (ChCl) compound as hydrogen bond acceptor and lactic acid (LA), oxalic acid (OA), potassium hydroxide or urea (UA) as the electrostatic attracting donors in different amount ratios, were synthetized, applied and studied for lignocellulosic biomass fractionation. The mixtures of ChCl with...

In this integrated in silico and experimental study, the activity, selectivity and mechanisms of commercially-available noble and transition metal heterogeneous catalysts, on neutral (carbon) support were investigated for hydrodeoxygenation (HDO) of eugenol. The latter was selected as a model compound of lignin building blocks. An influence of the...

Hydrotreatment of bio-based model compounds was investigated in a three-phase slurry reactor over pre-sulphided NiMo/γ-Al2O3 bifunctional catalyst. Experimental results were supported by comprehensive in silico studies. Mathematical microkinetic model was developed for mass transfer phenomena, adsorption, desorption and surface kinetics description...

Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing sur...

A facile and replicable stepwise chemical method was explored to synthesise magnetically separable Ru-based nanocatalyst. Structural investigation revealed that nanocatalyst is a hierarchical multiphase nanocomposite, consisting of highly magnetic Fe3C (and Fe) nanoparticles, distributed within a high-surface-area graphitic carbonaceous matrix, uni...

• Deterministic NH3-SCR kinetic model has been developed in Matlab™ 2016b environment and accounts velocity profile and mass transfer in a rectangular channel, as well as homogeneous, surface and adsorption/desorption kinetics. • Fluid dynamics through the pipe and inserted monolith was verified by CFD. • Laminar flow was found in a tube in front o...

Catalytic hydrogenation and deoxygenation reactions of ligno-cellulosic (LC) biomass resources are the main valorisation routes of bio-based oxygenates in bio-refineries. Eugenol is a model compound for lignin, which is besides cellulose and hemicellulose a major constituent of wood. Hydrodeoxygenation of eugenol on a Ru(0001) catalyst and in bulk...

This conference contribution will present a novel technology for renewable ash-free fuel production from low-value ash-containing feedstocks such as sludge digestate, wood bark or rice husks that cannot be utilized directly as a heating fuel, because of the high (low melting point) ash content. Biomass Ash Removal (BiAR) process introduces the low-...

Heterogeneous catalytic hydrotreatment is recognized as a key valorization route of bio-based oxygenates in a bio-refinery concept. Catalytic hydrodeoxygenation (HDO) and hydrogenation of eugenol, a lignin building block model component, was investigated in silico and experimentally in a three-phase slurry reactor over the ruthenium supported on ca...

Levulinic acid (LA) hydrotreatment at solvent-free conditions was studied in a slurry reactor over the sulphide form of NiMo/Al2O3 catalyst. The influence of process parameters on the H2 equilibrium solubility in the liquid (calculated by Soave–Redlich–Kwong, EOS), on the external and internal mass transfer limitations, adsorption and desorption ra...

Hydrotreatment of secondary hexanone and hexanol, and primary hexene species was investigated over the sulphide-form NiMo/γ-Al2O3 heterogeneous catalyst within the process temperature range 200–275 °C. The mechanistic microkinetic model for a three-phase slurry reactor was developed, comprising the mass transfer flux from the dispersed gaseous H2 b...

The development and evaluation of a new apparatus for the determination of high-pressure phase equilibria is presented. With this very versatile apparatus different experimental methods can be applied: the synthetic-visual, the synthetic-nonvisual, the synthetic-isothermal and the analytical-isothermal method. It allows visual observation of the en...

The one-step solvolysis and hydro-treatment of oak, fir and beech sawdust was studied in a slurry reactor using tetralin, phenol and glycerol as solvents and representative heterogeneous catalysts used in the petrochemical industry for hydrogenolysis (the sulfide form of NiMo/Al2O3), hydrogenation (Pd/Al2O3) or fluid catalytic cracking (zeolite Y)....

The tropospheric aqueous-phase aging of guaiacol (2-methoxyphenol, GUA), a lignocellulosic biomass burning pollutant, is addressed in this work. Pathways of GUA nitration in aqueous solution under atmospherically relevant conditions are proposed and critically discussed. The influence of NaNO2 and H2O2, hydroxyl radical scavenger, and sunlight was...

The tropospheric aqueous-phase aging of guaiacol (2-methoxyphenol, GUA), a lignocellulosic biomass burning pollutant, is addressed in this work. Pathways of GUA nitration in aqueous solution under atmospherically relevant conditions are proposed and discussed from a kinetic perspective. Beside reactions with nitrite radicals (NO2•), nitronium ion (...