Hanna Grabowska

Bio: Hanna Grabowska is an academic researcher from Polish Academy of Sciences. The author has contributed to research in topics: Catalysis & Alkylation. The author has an hindex of 17, co-authored 56 publications receiving 926 citations.

Some catalytic properties of hydrothermally synthesised zinc aluminate spinel

Abstract: Two samples of zinc aluminate were hydrothermally synthesised from zinc acetate and different aluminium sources: basic aluminium nitrate or aluminium hydroxide. The textural properties of the prepared ZnAl2O4 samples are different from these one of the zinc aluminate prepared by conventional way. Powder XRD and TEM measurements reveal that samples are single-phase material or mixture of ZnAl2O4 with small amount of γ-Al2O3, with morphology of quasi-spherical shape. Catalytic properties of the hydrothermally obtained zinc aluminate and Pt (Pd) catalysts supported on them were investigated in the reactions of cyclohexene isomerisation and combustion of trichloroethylene, respectively. It was evidenced that activity and selectivity of the investigated materials could be qualitatively correlated with the part of the strong acid centres measured by TPD of NH3.

A method for obtaining thymol by gas phase catalytic alkylation of m-cresol over zinc aluminate spinel

Abstract: The gas-phase catalytic alkylation of m -cresol with isopropanol on ZnAl 2 O 4 catalysts of different properties has been studied. The reactions were carried out in a continuous process at atmospheric pressure in the temperature range of 473–583 K. Both, O- and C-alkylated products were obtained at lower temperatures while at higher temperatures thymol was the main product of the reaction. According to the elaborated method thymol can be efficiently obtained with selectivity reaching up to 88.4% at an m -cresol conversion of 78.2%.

Photoluminescence and cathodoluminescence of Tb-doped Al2O3-ZrO2 nanostructures obtained by sol-gel method

Abstract: Terbium-doped Al2O3–ZrO2 mixed oxides of 10 wt% zirconia content were prepared by the alkoxide sol–gel method The obtained samples were characterized by XRD, SEM, thermal analysis, textural and TPR studies The effect of thermal treatment of Tb-doped Al2O3–ZrO2 samples on photo- and cathodoluminescence spectra was investigated It was found that the photoluminescence spectrum induced by UV excitation was characterized by a green luminescence pattern arising from the 5D4 → 7FJ (J=6–0) transitions of the Tb3+ ion This photoluminescence became almost completely damped for the samples sintered at 1200 °C However, these samples have demonstrated an intense cathodoluminescence under high electron accelerating potential (60 kV) Moreover, it was observed that apart of the green luminescence, the blue emission lines arising from 5D3 → 7FJ transitions of Tb3+ were observed The nature of such behavior is discussed

Catalytic fast pyrolysis of lignocellulosic biomass

Abstract: Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating value, high corrosiveness, high viscosity, and instability; they also greatly limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

Catalytic routes for the conversion of biomass into liquid hydrocarbon transportation fuels

Abstract: Concerns about diminishing fossil fuel reserves along with global warming effects caused by increasing levels of CO2 in the atmosphere are driving society toward the search for new renewable sources of energy that can substitute for coal, natural gas and petroleum in the current energy system. Lignocellulosic biomass is abundant, and it has the potential to significantly displace petroleum in the production of fuels for the transportation sector. Ethanol, the main biomass-derived fuel used today, has benefited from production by a well-established technology and by partial compatibility with the current transportation infrastructure, leading to the domination of the world biofuel market. However, ethanol suffers from important limitations as a fuel (e.g., low energy density, high solubility in water) than can be overcome by designing strategies to convert non-edible lignocellulosic biomass into liquid hydrocarbon fuels (LHF) chemically similar to those currently used in internal combustion engines. The present review describes the main routes available to carry out such deep chemical transformation (e.g., gasification, pyrolysis, and aqueous-phase catalytic processing), with particular emphasis on those pathways involving aqueous-phase catalytic reactions. These latter catalytic routes achieve the required transformations in biomass-derived molecules with controlled chemistry and high yields, but require pretreatment/hydrolysis steps to overcome the recalcitrance of lignocellulose. To be economically viable, these aqueous-phase routes should be carried out with a small number of reactors and with minimum utilization of external fossil fuel-based hydrogen sources, as illustrated in the examples presented here.

Nanocatalysts for Suzuki cross-coupling reactions

Abstract: This critical review deals with the applications of nanocatalysts in Suzuki coupling reactions, a field that has attracted immense interest in the chemical, materials and industrial communities. We intend to present a broad overview of nanocatalysts for Suzuki coupling reactions with an emphasis on their performance, stability and reusability. We begin the review with a discussion on the importance of Suzuki cross-coupling reactions, and we then discuss fundamental aspects of nanocatalysis, such as the effects of catalyst size and shape. Next, we turn to the core focus of this review: the synthesis, advantages and disadvantages of nanocatalysts for Suzuki coupling reactions. We begin with various nanocatalysts that are based on conventional supports, such as high surface silica, carbon nanotubes, polymers, metal oxides and double hydroxides. Thereafter, we reviewed nanocatalysts based on non-conventional supports, such as dendrimers, cyclodextrin and magnetic nanomaterials. Finally, we discuss nanocatalyst systems that are based on non-conventional media, i.e., fluorous media and ionic liquids, for use in Suzuki reactions. At the end of this review, we summarise the significance of nanocatalysts, their impacts on conventional catalysis and perspectives for further developments of Suzuki cross-coupling reactions (131 references).

Sustainable Preparation of Supported Metal Nanoparticles and Their Applications in Catalysis

Abstract: Metal nanoparticles have attracted much attention over the last decade owing to their unique properties as compared to their bulk metal equivalents, including a large surface-to-volume ratio and tunable shapes. To control the properties of nanoparticles with particular respect to shape, size and dispersity is imperative, as these will determine the activity in the desired application. Supported metal nanoparticles are widely employed in catalysis. Recent advances in controlling the shape and size of nanoparticles have opened the possibility to optimise the particle geometry for enhanced catalytic activity, providing the optimum size and surface properties for specific applications. This Review describes the state of the art with respect to the preparation and use of supported metal nanoparticles in catalysis. The main groups of such nanoparticles (noble and transition metal nanoparticles) are highlighted and future prospects are discussed.