Rafael Luque

• Chemistry
• Professor (Full) at King Saud University

Supplementary

The hydroconversion of cinnamaldehyde as an α,β-unsaturated compound was studied using a simple and efficient hydrogen-donating protocol catalyzed by mechanochemically synthesized bifunctional Pd/ Al-SBA-15 catalysts. Materials were characterized using TGA-TDA, nitrogen physisorption, TEM and EDX analyses. Catalytic results pointed to the presence of...

Hydrogenation of levulinic acid (LA) towards γ-valerolactone (GVL) is one of the most promising reactions in the field of biomass valorization to fine chemicals and liquid transportation fuels. GVL has been recently considered as a new renewable liquid for gasoline and diesel fuel oxygenates due to its comparable fuel characteristics to those of fo...

The continuous flow hydroconversion of furfural to a range of furanic derivatives was carried out using a range of metal-containing heterogeneous catalysts in order to provide insights into reaction pathways for the hydrogenation of furfural. Most catalysts provided excellent furfural conversion (>60%) and varying selectivities to products at mild...

This work was aimed to provide additional insights into lignin deconstruction using different sources of lignin (ranging from softwoods to hardwoods) mediated by NiO containing ZSM-5 materials under the pyrolysis.

A simple and effective ultrasound-assisted wet impregnation method was developed for the preparation of magnetically separable TiO2/maghemite-silica photo-active nanocomposites. The resulting nanomaterials were characterized by several techniques and subsequently tested for their photocatalytic activities in the liquid phase selective oxidation of...

Earth-abundant, active and stable water splitting electrocatalysts operating in the same electrolyte at all pH values is important for many renewable energy conversion processes. We report here the first carbon nanomaterials-based metal-free water splitting electrocatalyst. The nitrogen, phosphorus and oxygen tri-doped porous graphite [email protec...

Polysaccharides extracted from microorganisms can be used as nanoparticle carriers and sacrificial templates for the design of nanohybrid materias. Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications. M...

Continuous flow processes can provide a number of significant benefits for synthesis/reaction processing of nanomaterials as compared to batch reactor technologies. Under continuous flow conditions, advantages including simplicity in preparation and operation, process control (flow rate, temperature, etc.), flexibility, higher productivity and cont...

Flavouring compounds are extensively utilised in our current society. The need for synthetic routes that allow us to obtain such chemicals has become one of the main goal in the research community. New synthetic routes have to respect the environment and simultaneously provide high quality products without wasting natural sources, not possible by t...

A simple, innovative and efficient continuous flow methodology for the direct preparation of supported nanoparticles on porous materials using metal precursor solution flowing through heated packed-bed reactors containing the support material has been developed. The main objective of the work was to study the deposition of iron oxide (Fe2O3) nanopa...

Surfactant-free tiny Pt clusters were successfully encapsulated within MOFs with controllable size and spatial distribution by a novel kinetically modulated one-step strategy. Our synthesis relies on the rational manipulation of the reduction rate of Pt ions and/or the growth rate of MOFs by using H2 as assistant reducing agent and/or acetic acid a...

Hydrogenation of levulinic acid (LA) towards γ-valerolactone (GVL) is one of the most promising reactions in the field of biomass valorization to fine chemicals and liquid transportation fuels. Bimetallic Ni-Pt and Ni-Ru supported on ZrO2 and γ-Al2O3 were successfully utilized in this work as highly active and GVL-selective catalysts for the solven...

Food supply chain waste (FSCW) is causing environmental and financial issues across the world, but if considered as a resource rather than a waste, it is possible to derive significant value through its exploitation to chemicals, materials, and fuels. Researchers across Europe and the world are trying to find innovative solutions to the food waste...

The conversion of renewable biomass resources into fuels, polymers, and fine chemicals provides solutions for the growing shortage of fossil resources, environmental pollution and a possible crisis in energy supply. 5-Hydroxymethylfurfural (HMF) as an important biomass-derived platform chemical, its selective oxidation to multifunctional molecules...

A new approach for the encapsulation of laccases with enhanced activity and stability by biomimetic silica mineralisation is reported. A range of lignin model compounds, which includes syringol, syringyl acid, 4-vinylphenol, gallic acid, vanillic acid and guaiacol, was oxidised to lignin-type polymers by the silica-immobilised laccase systems at ro...

Pd nanoparticles deposited onto graphene oxide nanosheets (SE-GO/PdNPs) were found to successfully promote two oxidative processes for the synthesis of amides, providing alternative possibilities to these important compounds. SE-GO/PdNPs exhibited excelling activities with an optimum efficiency in tandem one-pot conversion of alcohol to amides in t...

Aerobic oxidation of carbohydrate-derived 5-hydroxymethylfurfural (HMF) into high added-value 2,5-diformylfuran (DFF) has attracted much attention in recent years. However, the direct synthesis of DFF from cheap and abundant carbohydrates via HMF as an intermediate through a one-pot process is highly desirable but challenging. In this work, we have...

Catalytic valorisation of biomass with solid functional materials has been recognised as a promising approach to produce value-added biochemicals and biofuels. Furanic compounds such as 5-hydroxymethylfurfural (HMF), 5-ethoxymethylfurfural, 2,5-dimethylfuran, 2,5-diformylfuran and 2,5-furandicarboxylic acid can be obtained from hexoses and pentoses...

A series of crown-jewel Pd-based bimetallic nanostructures with tunable composition are fabricated inside the pores of an MOF via a hydride-induced-reduction strategy, exhibiting high activity and stability in the hydrogenation of nitrobenzene.

Handbook of Biofuels Production, Second Edition, discusses advanced chemical, biochemical, and thermochemical biofuels production routes that are fast being developed to address the global increase in energy usage. Research and development in this field is aimed at improving the quality and environmental impact of biofuels production, as well as th...

Europe currently recycles less than one third of it’s waste. Biomass and food waste could be used as a renewable feedstock for valuable chemicals and fuels. In times of declining fossil stocks, science and industry have to find alternative resources for the production of fuels and chemicals. This book presents techniques for the utilization of biom...

Biofuel is a rapidly growing research field and fast-moving industry. Since the publication of the first edition of Handbook of Biofuels Production in 2011, significant research progresses in biofuel production technology have been made, improved understanding of biofuel production processes has been acquired, and the industrial production of biofu...

This chapter discusses general considerations on gasification processes and synthetic liquid fuel production. It provides an overview of state-of-the-art gasification technologies, feedstocks and applications in power generation, and synthetic fuels production, together with some recent future trends in the field.

Biomaterials and sustainable resources are two complementary terms supporting the development of new sustainable emerging processes. In this context, many interdisciplinary approaches including biomass waste valorization and proper usage of green technologies, etc., were brought forward to tackle future challenges pertaining to declining fossil res...

The development of room temperature catalytic protocols recently emerged as a promising alternative to minimize energy consumption in catalytic reactions, at the same time, obtaining high product yields and/or better atom economies (lowering byproduct generation). This chapter discusses the catalytic performances achieved in various chemical reacti...

This contribution discloses a simple and efficient procedure using environmentally benign supported cobalt nanocatalyst for the synthesis of bis(indolyl)methanes under solvent-free conditions. The supported cobalt nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity, prov...

Lignin depolymerisation has recently a great deal of attention from scientists and companies worldwide due to the extensive possibilities of this recalcitrant material for the production of chemicals, fuels and materials. The natural complexity and stability of lignin bonds makes lignin depolymerization a highly challenging task. Several efforts ha...

Carbon materials have been extensively investigated due to their diversity, favorable properties, and active applications including electroanalytical chemistry. This critical review discusses new synthetic methods, novel carbon materials, new properties and electroanalytical applications of carbon materials particularly related to the preparation a...

Organocatalytic enamine-azide [3 + 2] cycloadditions between β-keto sulfones and aryl azides can be performed at room temperature in good to excellent yields of products in the presence of catalytic amounts of pyrrolidine (5 mol %). The proposed organocatalytic methodology was found to be applicable to β-keto arylsulfones containing a range of subs...

Deconstruction of lignocellulosic biomass using enzymatic catalysis can offer several advantages as compared to chemical catalysis in terms of product selectivity, production cost and sustainability issues. This contribution aims to provide an account of current developments in the understanding of plant biomass microstructures and the impact of va...

The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination c...

The addition of phenols to styrene to form ortho and para-(1-phenylethyl) phenols was catalysed by a range of metal oxide nanoparticles supported on mesoporous aluminosilicates (M/Al-SBA-15 catalysts) under microwave irradiation. Moderate to excellent yields to products could be obtained at short times of reaction (typically 10 min). 0.5%Fe/Al-SBA-...

A continuous‐flow protocol for the gold‐catalyzed cycloisomerization of sterically hindered Ugi‐adducts to spiroindolines in a packed‐bed reactor is presented. Spiroindolines with various substitution patterns are formed in good yields and with good selectivity. A detailed characterization of the catalyst deactivation process was conducted, whereas...

In this work a microwave-assisted depolymerisation of lignin in the presence of zeolite-based catalysts was studied in order to obtain a valuable bio-oil. Catalytic activity of H-ZSM-5, H-Y, H-BETA and H-Mordenite containing nano-NiO particles was investigated in the depolymerisation of Biolignin TM. The catalysts were prepared by mechanochemical d...

A selective, efficient and benign oxidative coupling of benzylamine under microwave irradiation was achieved at mild reaction conditions in the absence of oxidant using graphene oxide as catalyst. Reaction conditions seem to point to the favoured formation of an imine intermediate which subsequently reacts with benzylamine to provide high selectivi...

A comparative study of the influence of three different acid solids as catalysts (conventional zeolites Z15c with Si/Al = 19.5 and Z40c with Si/Al = 48.2, and a hierarchical zeolite Z40c-H with Si/Al = 50.0) for the etherification of glycerol with benzyl alcohol was performed. The catalytic activity and selectivity of these zeolites was elucidated...

The possibility of using inner cavities within metal–organic frameworks (MOFs) as templates for the fabrication of tiny metal nanoparticles (NPs) was attempted in this work. An unprecedented design of Pd@Ag core–shell NPs on MOFs via a seed mediated growth strategy is reported and attributed to the presence of activated physisorbed hydrogen atoms o...

Mechanochemically synthesized ZnO-polysaccharide nanohybrids prepared from fungal polysaccharides were proved to exhibit remarkable surface properties and structures for biomedical applications. The synthesized ZnO nanomaterials possessed an unprecedented low cytotoxicity against human cell lines A549 and SH-SY5Y (EC50: 50-100 μg mL-1) as compared...

The microwave-assisted conversion of levulinic acid (LA) has been studied using low-loaded supported Fe-based catalysts on porous silicates. A very simple, productive, and highly reproducible continuous flow method has been used for the homogeneous deposition of metal oxide nanoparticles on the silicate supports. Formic acid was used as a hydrogen...

High-performance monodispersed chitosan microparticles for methyl orange (MO) adsorption were synthesized on a microfluidic platform coupled with a cross-linking approach. Batch adsorption experiments were carried out to evaluate the capacity and kinetics of the as-prepared microparticles on the adsorption of MO. Due to the advantage of microfluidi...

Graphene oxide (GO) was investigated as a catalyst in the oxidation of alkenes and alkynes in combination with microwave heating. Styrene and phenylacetylene were selected as model compounds for the study. Moderate catalyst loadings (25 wt.%) and short reaction times (1 h) were employed, demonstrating that the combination of GO and H2O2 under micro...

This chapter provides a survey of microwave-assisted organic reactions performed in both organic and aqueous solvents. Most organic reactions are performed using a homogeneous/heterogeneous catalyst for a few hours. The convenience of microwave irradiation has allowed these types of syntheses to be performed in only a few minutes. Employing microwa...

A novel class of bionanocomposites based on monodisperse microparticles containing metal nanoparticles including Au, Pd, Ag and Pt were synthesized and characterized using a simple and efficient approach. The versatile nanocomposites exhibited unique possibilities as new biosensor for highly selective and sensitive immunoassays as well as a remarka...

Pt-based bimetallic alloy nanomaterials with a low Pt loading can exhibit promising catalytic properties with exciting electrochemical applications. An effective structure control of Pt-based bimetallic alloy nanomaterials is critical to achieve enhanced catalytic properties. This review article focuses on recent advances in the controllable synthe...

Benzimidazole derivatives have attracted a significant attention in recent years because of their medicinal applications as antiviral, antiulcer, antifungal, antihypertensive, anticancer, and antihistamine compounds. The one-pot synthesis of benzimidazole derivatives via oxidative condensation of aromatic aldehydes with o-phenylenediamines under mi...

Continuous-flow liquid phase oxidation chemistry in microreactors receives a lot of attention as the reactor provides enhanced heat and mass transfer characteristics, safe use of hazardous oxidants, high interfacial areas, and scale-up potential. In this review, an up-to-date overview of both technological and chemical aspects of liquid phase oxida...

The selective hydrogenation of furfural into cyclopentanone is an attractive transformation to advance in the sustainable synthesis of important chemicals from biomass. A supported Ru nanoparticle catalyst on an acidic MOF material (Ru/MIL-101) was designed for the highly active and selective conversion of furfural to cyclopentanone in aqueous medi...

The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid...

Abstract The catalytic performance of highly active cobalt(II) supported on mesoporous SBA-15 materials for the Pechmann reaction was investigated. SBA-15 supported cobalt(II) nanocatalyst was found to be efficient and easily recoverable in the Pechmann reaction of phenols and β-ketoesters to their corresponding coumarin derivatives under solvent-f...

We report the utilization of a novel catalyst for cycloisomerizations. The novel catalyst system contains gold nanoparticles supported on Al-SBA15, which was prepared by the ball-milling process, ensuring that the majority of the metal is deposited on the surface and not inside the pores of the support. We developed a greener methodology for synthe...

Being green: At the recent 248th ACS Spring Meeting in San Francisco, CA (USA), Professor Sherine Obara and Professor Rafael Luque brought together a number of scientists in a symposium focused on the merits of green chemistry for a sustainable future. The symposium, entitled “Green Chemistry and the Environment” offered a broad and multifaceted vi...

Novel heterogeneous catalyst systems comprised of palladium nanoparticles immobilized into the nanospaces of imidazolium-based bifunctional plugged and unplugged periodic mesoporous organosilicas (BFPMO) have been described for the selective aerobic oxidation of alcohols in water. BFPMOs were characterized by N2 adsorption-desorption analysis, tran...

A pluronic P123 surfactant was employed in the exfoliation and stabilization of Pd0-supported graphene oxide (PdNPs–GO; NPs=nanoparticles) nanosheets in aqueous solution during the oxidation of benzylic and aliphatic alcohols under aerobic conditions at 80 °C. Surfactants prevented the aggregation of PdNPs–GO sheets at 80 °C under aqueous condition...

Novel biomass-derived porous carbons are attractive candidates for the preparation of carbon-supported catalysts with a wide range of catalytic applications. Such carbonaceous catalysts are environmentally benign and could provide a cost-competitive advantage as compared to existing heterogeneous catalysts. Tunable surface properties of carbon mate...

Novel biomass-derived porous carbons are the leading candidates to make carbonaceous-supported catalysts for a wide range of catalytic applications. According to the green chemistry principles, biomass-based carbonaceous catalysts are environmentally benign and highly economical as compared to the other existing heterogeneous catalysts. Tunable sur...

A simple, innovative and efficient continuous flow methodology for the direct preparation of supported nanoparticles on porous materials using metal precursor solution flowing through heated packed-bed reactors containing the support material has been developed. The effect of the flow rate of the precursor solution, temperature and nature of the su...

The preparation of supported Pd nanoparticles on porous materials (Al-SBA-15 and Al MCF) was successfully achieved using a simple, fast and efficient reactive milling (mechanochemical) method. Upon preparation, catalysts were characterized by N2 physisorption, elemental analysis, Transmission Electron Microscopy (TEM) and X ray diffraction (XRD). T...

Hierarchical ZSM-5 zeolites prepared using a simple alkali treatment and subsequent HCl washing are found to exhibit unprecedented catalytic activities in selective oxidation of benzyl alcohol under microwave irradiation. The metal-free zeolites promote the microwave-assisted oxidation of benzyl alcohol with hydrogen peroxide in yields ranging from...

Solvothermal synthesis has advanced significantly over the past decades and became a versatile approach to achieve the morphology control of well-defined metal nanostructures. This review covers the most recent progress on the solvothermal syntheses and applications of metal nanocrystals. Key synthetic factors are summarized, including temperature,...

Novel ordered two-dimensional (2D) hexagonal plugged and non-plugged bifunctional periodic mesoporous organosilicas (BFPMO) with variable content of bridged IL-phenyl or -ethyl units have been prepared using Pluronic P123 as a supramolecular structure directing agent (SDA) in acidic media. The final solvent extracted BFPMOs have been characterized...

Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications. Featuring simplicity, high reproducibility, mild/short reaction conditions and often solvent-free condition (dry milling), mechanochemistry can offer...

Porous carbon materials are at the heart of many applications, including renewable energy storage and generation, due to their superior physical properties and availability. The environmentally-friendly production of these materials is crucial for a sustainable future. This book focuses on the transformation of sustainable precursors into functiona...

Biomass can efficiently replace petroleum in the production of fuels for the transportation sector. One effective strategy for the processing of complex biomass feedstocks involves previous conversion into simpler compounds (platform molecules) which are more easily transformed in subsequent upgrading reactions. This contribution is aimed to provid...

Platinum highly concave cubes with one leg on each vertex (HCCLV) enclosed by {7 5 0} facets were conveniently synthesized for the first time through a one-pot solvothermal method in a mixed solvent of oleylamine and isopropanol containing platinum(II) acetylacetonate. This method can also be extended to the synthesis of Pt dendrite nanocubes at sh...

Optimización en las condiciones de síntesis de nanopartículas de óxido de hierro soportadas mediante procesos de flujo continuo.

Actividad catalítica de los diferentes aluminosilicatos sintetizados en la conversión de disoluciones acuosas de almidón a productos de valor añadido.

The synthesis of esters has become an important industrial methodology over the past years because of the role that they serve in the chemical industry. In this study, we present the use of a novel catalyst for the direct conversion of aldehydes into esters. The yields obtained using supported iron oxide nanoparticle catalysts (FeNP) are very high...

Co/SBA-15 nanoparticle catalysts (CoNP) were prepared using a commonly adapted synthetic route and then utilised for esterification and amidation reactions using aromatic and linear chain compounds for the production of long chain esters and amides. The study shows that the use of CoNP catalysts favours the use of aromatic reactants with electron d...

Microwaves have emerged as a very efficient source of heat for accelerating many chemical reactions and processes. Actually, ever growing demand of energy and concerns for the environment have prompted researchers to develop convenient and efficient ways for converting lignocellulosic biomass into valuable chemicals , bio-fuels and useful biomateri...

Pt-branched structures featuring concave and duck web-like nanopentagons (CWPNP), with surfaces enclosed by {111} facets, high-energy {110} and {554} facets, multiple twin boundaries, duck web-like edges and inherent anisotropic branches are herein reported. The unique chemisorption properties and reducing capacities of tri-n-propylamine and oleyla...

Green chemistry and engineering principles are central to advancements in fundamental research and development in academic, government and industrial sectors. Innovations in chemical design, development of new solvents or reducing/eliminating the use of solvents, and the processes that lead to sustainable practices, are essential toward a safe and...

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Core–shell silica comprising mesoporous SiO2 shell and solid SiO2 core (SiO2@mSiO2) was utilized as catalytic support to prepare highly active and efficient Au–SiO2@mSiO2 catalysts for room temperature catalysis. Results showed that the mesoporous shell significantly contributed to the high surface area of SiO2@mSiO2. Au nanocatalysts prepared by d...

A simple, innovative, and efficient continuous flow methodology for the direct preparation of supported nanoparticles on porous materials by using metal precursor solution flowing through heated packed-bed reactors containing the support material has been developed. The effects of the flow rate of the precursor solution, temperature, and nature of...

A multiscale-designed optofluidic reactor is demonstrated in this work, featuring an overall reaction rate constant of 1.32 s−1 for photocatalytic decolourization of methylene blue, which is an order of magnitude higher as compared to literature records. A novel performance-enhancement mechanism of microscale in situ photogalvanic acceleration was...

Glycerol conversion to valuable products has been a research avenue that attracted a significant interest in recent years due to its large available volumes (as by-product of biodiesel production) and the different possibilities for chemical and biological conversion into high added value chemicals profiting from the unique presence of three hydrox...

The generation of organic waste continues to increase, causing severe environmental pollution. Waste valorization is currently an emerging technology that can address this problem with an extra benefit of producing a range of valued products. In this contribution, we report the current developments in hydrotreating technologies for upgrading waste...

Desarrollo de una nueva metodología para la síntesis de nanopartículas de óxido de hierro soportadas sobre materiales porosos y comparación de su actividad catalítica con materiales análogos sintetizados mediante diferentes metodologías.

SBA-15 materials exhibit important properties including large surface area, highly ordered mesopores, and high stability in a variety of catalytic reactions. In this study, Al and Zr-loaded SBA-15 materials (Si/Zr = 30, Si/Al = 30), 50 molar ratio with Pd (1, 2, and 4% (w/w)) and Pt (0.5 and 1% (w/w)) were tested in the isomerization of C5–C7 linea...

A simple and innovative concept for a micro-aquaponic system (MAS) to valorize residual nitrogen via photocatalytic conversion was developed. Results proved that over 70% of ammonia could be oxidized to nitrates within 1.5 hours under UV irradiation and subsequently taken up by plants which experienced a remarkably superior plant growth (with resul...

Supported iron oxide nanoparticles have been incorporated onto hierarchical zeolites by microwave-assisted impregnation and mechanochemical grinding. Nanoparticle-functionalised porous zeolites were characterised by a number of analytical techniques such as XRD, N2 physisorption, TEM, and surface acidity measurements. The catalytic activities of th...

The plastic industry generates enormous quantities of plastics at projected rates (both production and consumption) which can significantly threaten our environment in terms of plastic waste generation. High density polyethylene (HDPE) is one of the main fractions of municipal solid waste which has a remarkable potential to be valorised into fuels...

Research on lignin deconstruction has recently become the center of interest for scientists and companies worldwide, racing towards harvesting fossil-fuel like aromatic compounds which are so durably put together by plants as products of millions of years of evolution. The natural complexity and high stability of lignin bonds (also as an evolutiona...

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