Jacek Grams

Ru catalysts for levulinic acid hydrogenation with formic acid as a hydrogen source

The catalytic hydrogenation of levulinic acid (LA) with formic acid (FA) as a hydrogen source into γ-valerolactone (GVL) is considered as one of the crucial sustainable processes in todays biorefinery schemes. In the current work, we investigated the modification of Ru/C as efficient catalysts for both formic acid decomposition and levulinic acid hydrogenation in comparison with Pd and Pt catalysts. In order to better understand what features are responsible for high catalytic performance, we combined experimental tests, DFT calculations together with extensive material characterization. In LA hydrogenation with FA as a hydrogen source, the intermediate surface formate inhibits at least partially the LA hydrogenation. In addition, the FA decomposition is highly sensitive to the kind of the preparation method of the Ru/C catalyst: (i) the process looks structure sensitive favored on larger particles and (ii) residual chlorine decreases significantly the FA decomposition rate.

Titania‐Supported Catalysts for Levulinic Acid Hydrogenation: Influence of Support and its Impact on γ‐Valerolactone Yield

A series of titania-supported ruthenium and platinum catalysts was investigated in the levulinic acid hydrogenation towards γ-valerolactone, a key reaction for the catalytic transformation of biomass. It was shown that various morphologies and phases of titania strongly influence the physicochemical and catalytic properties of supported Ru and Pt catalysts in different ways. In the case of the catalyst supported on mixed TiO2 phases, Ru particles are exclusively located on the minority rutile crystallites, whereas such an effect was not observed for platinum. The platinum catalyst activity could be increased when the metal was dispersed on the large surface-area anatase, which was not the case for ruthenium as a result of its agglomeration on this support. The activity of ruthenium on anatase could be increased in two ways: a) when RuO2 formation during catalyst preparation was avoided; b) when pure anatase support material was modified so that it exhibited no microporosity. The obtained results allow a better understanding of the role of the support for Ru and Pt catalysts.

Activity of Ni catalysts for hydrogen production via biomass pyrolysis

Ni catalysts were tested in the catalytic pyrolysis of biomass. The influence of Ni loading and various catalytic supports (ZrO2, Al2O3, ZrO2 + Al2O3, CeO2, SiO2) was studied. Although the gas phase was the main object of this study, solid and liquid residues were tested as well (mainly by TOC and GC-MS methods). Activity tests were performed in a batch reactor with mechanical stirring, equipped with on-line GC. Reaction was conducted at 700°C, with α-cellulose as a biomass model and with waste paper as an example of raw lignocellulosic material. Reactions in the presence of a catalyst gave a higher hydrogen yield. The most promising results were obtained with Ni/ZrO2.

Novel AuNbMCM-41 catalyst for methanol oxidation

The synthesis, characterization and catalytic application of bifunctional gold and niobium containing MCM-41 molecular sieves are reported for the first time. It is shown that Au is better dispersed when introduced during the synthesis than if it is deposited via impregnation. Moreover, it is evidenced that the introduction of Nb besides gold in the MCM-41 framework significantly shifts the oxidation of methanol towards formaldehyde (industrially important compound) at relatively low reaction temperature.

Characteristic of physicochemical properties of Pd/MgO catalysts used in the hydrodechlorination process with CCI4

Characteristic of physicochemical properties of Pd/MgO catalysts used in the hydrodechlorination process with CCI4 The aim of this paper was to investigate the physicochemical properties of palladium catalyst containing basic support MgO which was used in hydrodechlorination reaction with carbon tetrachloride. In order to characterize the investigated sample the catalyst was put to tests of XRD, TOF - SIMS, TG-DTA-MS and TPRH2 measurements, activity tests were also performed. The XRD and TPR results demonstrated the presence of PdOxCly species whose decomposition takes place above 700°C. The calcination of the Pd/MgO catalyst at 700°C resulted in the transformation of PdOxCly to PdO.

The Studies of Archaeological Pottery with the Use of Selected Analytical Techniques

ABSTRACT Modern analytical methods play an important role in archaeological objects, including ceramics. This review focuses on the use of analytical methods such as: gas chromatography coupled mass spectrometry, Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), powder X-ray diffraction with thermal analysis to study the chemical and mineralogical composition of archaeological samples and organic residues preserved inside. In this paper, special attention was paid to the ToF-SIMS method, which allows the determination of characteristic ions on the surface of ceramic samples.

Hydrogen production from biomass woodchips using Ni/CaO–ZrO2 catalysts

This work aimed at the determination of the influence of various types of lignocellulosic biomass on the performance of Ni/ZrO2 catalyst modified by CaO in the production of hydrogen rich gas from lignocellulosic feedstock. The catalysts were prepared by co-impregnation and sequential impregnation methods. The catalytic activity of the synthesized materials was examined in the high temperature conversion of cellulose (model compound) and real biomass samples—woodchips from pine, beech, birch and poplar. The surface properties of Ni/CaO–ZrO2 catalysts were characterized by X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (ToF–SIMS), thermogravimetric analysis (TG–DTA–MS) and BET methods. The obtained results revealed that an incorporation of calcium into the structure of the catalyst led to a decrease in the coke formation rate on its surface. Moreover, the influence of the preparation method on the material composition and related properties was demonstrated.

Enhanced production of -valerolactone with internal source of hydrogen on Ca-modified TiO2 supported Ru catalysts

Calcium-modified titania supported Ru catalysts were synthesized and evaluated for the hydrogenation of levulinic acid with formic acid as an internal hydrogen source and water as a green solvent. A new elegant photoassisted method was developed for the synthesis of uniform-size and evenly distributed Ru particles on the titania surface. Compared with the counterpart catalysts prepared by classical wet impregnation, enhanced levulinic acid conversion and γ-valerolactone yield were obtained and further improved through modification of the support by introduction of calcium into the titania support. This synthesis approach resulted in a change of the surface and bulk properties of the support, namely a decrease in the anatase crystallite size and the formation of a new calcium titanate phase. As a consequence, the properties of the catalysts were modified, and smaller ruthenium particles that had stronger interactions with the support were obtained. This affected the strength of the CO adsorption on the catalyst surface and facilitated the reaction performance. The optimum size of Ru particles that allowed for most efficient levulinic acid conversion was established.

Supported gold–nickel nano-alloy as a highly efficient catalyst in levulinic acid hydrogenation with formic acid as an internal hydrogen source

Gamma-valerolactone (GVL) is one of the key products of future biorefineries. We show here for the first time the superior activity of Ni-based, Au doped catalysts in levulinic acid hydrogenation towards GVL using formic acid as a hydrogen source. Their performances are strongly influenced by the preparation method, and the highest GVL yield is achieved for bimetallic Au–Ni catalysts prepared via co-impregnation of both metallic salts with a reductive thermal treatment under hydrogen. The very high catalytic activity is explained by the use of DFT calculations and the extensive characterization of the catalyst surface and bulk properties. We highlight the pivotal role played by the incorporated isolated metallic Ni atoms within Au nanoparticles. The nano-alloy composition is determined. It allows establishment of a surface model of such an alloy, thanks to which the high activity can be explained by the presence of an optimum energetic span of FA adsorption. The existence of strong interaction between Au and Ni in a surface alloy, Au–Ni, favors selective and fast decomposition of formic acid into hydrogen that consequently facilitates strongly the combined hydrogenation process.

Surface characterization of different particles arising as a result of coal combustion process in selected power plants from Central Poland using ToF-SIMS

Surface characterization of different particles arising as a result of coal combustion process in selected power plants from Central Poland using ToF-SIMS The aim of this work was the ToF-SIMS investigations of different particles arising as a result of a coal combustion process in selected power plants from Central Poland. The chemical composition and distribution of particular compounds on the studied surfaces were determined. Moreover, the ratio of the quantity of aromatic and aliphatic hydrocarbons adsorbed on the surface of the particles was estimated. A qualitative analysis of the studied samples demonstrated the presence of a big number of various compounds, including heavy metals such as Pb, Cd and As on the investigated surfaces. In the prevailing number sample components were distributed non-homogenously on the surface and the larger areas richer in a certain type of ions were observed.