Hydrogen production from oxidative steam-reforming of n-propanol over Ni/Y 2O 3-ZrO 2 catalysts

Oxidative steam reforming (OSR) of n-propanol was studied over new Ni catalysts (ca. 7% Ni wt/wt) supported on Y 2O 3-ZrO 2 oxides with different yttrium content (2-41 % Y 2O 3 wt/wt). Materials were characterized by X-ray diffraction, temperature-programmed reduction, X-ray photoelectron and Raman spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis and high resolution transmission electron microscopy. Samples were used in calcined form and tested in the temperature range 673-773 K using a reactant feed of n-propanol/water/O 2 at a molar ratio 1/9/0.5. Hydrogen production is related with the support composition and Ni dispersion. Copyrigh

A novel approach to the production of biochar with improved fuel characteristics from biomass waste

This paper examines the potential for using forward self-sustaining smouldering for the oxidative pyrolysis/torrefaction of lignocellulosic biomass, aiming to produce biochar with fuel characteristics. A vertical, fixed-bed reactor was used for this purpose, where an upwards air flow acted as oxidant. Once smouldering is initiated, the reaction is sustained without the need of supplementary energy. The biochar production was studied at three different airflow rates. In order to perform a systematic study, commercial wood pellets were used for this proof-of-concept. The wood pellets and the biochar obtained were characterized by means of elemental, proximate and thermogravimetric analyses. Results showed that the airflow rate can be used to control the temperature of the process and therefore, the characteristics of the final product. Energy densifications of up to 70% were obtained, and it has shown to increase with the airflow rate. The resulting biochar in the best case scenario has a HHV of 31.3 kJ/g, along with an atomic O/C and H/C ratios of 0.009, and 0.338 respectively. The Van Krevelen diagrams of the biochar samples suggested that energy densification is due to the loss of compounds containing hydrogen and oxygen. The increase of the airflow used during the process showed a reduction in the content of alkali and alkaline earth metallic species in the products, which is desired for its application as solid fuel. This proof-of-concept showed promising results towards the development of an on-site, sustainable, cost effective and continuous process for the torrefaction/pyrolysis of lignocellulosic residue from harvesting operations

Improved yield parameters in catalytic steam gasification of forestry residue; optimizing biomass feed rate and catalyst type

The catalytic gasification (900 °C) of forestry industry residue (Eucalyptus saligna) was laboratory-studied. Biomass feed rate and type and amount of catalyst were assayed for their effect on the gasified product composition and the overall energy yield of the gasification reaction. The use of a calcined dolomite catalyst resulted in a combustible gas mixture of adequate calorific power (10.65 MJ m -3) for use as fuel, but neither the product gas composition nor the energy yield varied significantly with widely different amounts of the catalyst (2 g and 20 g). The use of NiO-loaded calcined dolomite catalysts did not affect the product gas composition significantly but led to a 30% increase in the total product gas volume and to a reduction in the rate of tar and char formation. The catalyst loaded with the smallest amount of NiO studied (0.4 wt%. Ni/Dol) led to the highest energy yield (21.50 MJ kg -1 on a dry-wood basis) based on the use of the gasified product as fuel. The gasified product was found to have an adequate H 2/CO molar ratio and H 2 content for use as synthesis gas source and partial source of H 2

Calibrating the coordination chemistry tool chest: metrics of bi- and tridentate ligands

Bi- and multidentate ligands form part of the tools commonly used for designing coordination and supramolecular complexes with desired stereochemistries. Parameters and concepts usually employed include the normalized bite of bidentate ligands, their cis- or trans-coordinating ability, their rigidity or flexibility, or the duality of some ligands that can act in chelating or dinucleating modes. In this contribution we present a structural database study of over one hundred bi- and tridentate ligands that allows us to parametrize their coordinating properties and discuss the relevance of such parameters for the choice of coordination polyhedron or coordination sites

H2 production from oxidative steam reforming of 1-propanol and propylene glycol over yttria-stabilized supported bimetallic Ni-M (M = Pt, Ru, Ir) catalysts

This paper reports hydrogen production from oxidative steam reforming of 1-propanol and propylene glycol over Ni-M/Y2O3-ZrO 2 (10% wt/wt Y2O3; M = Ir, Pt, Ru) bimetallic catalysts promoted with K. The results are compared with those obtained over the corresponding monometallic catalyst. The catalytic performance of the calcined catalysts was analyzed in the temperature range 723-773 K, adjusting the total composition of the reactants to O/C = 4 and S/C = 3.2-3.1 (molar ratios). The bimetallic catalysts showed higher hydrogen selectivity and lower selectivity of byproducts than the monometallic catalyst, especially at 723 K. Ni-Ir performed best in the oxidative steam reforming of both 1-propanol and propylene glycol. The presence of the noble metal favours the reduction of the NiO and the partial reduction of the support. The NiO crystalline phase present in the calcined catalysts was transformed to Ni during oxidative steam reforming. The adsorption and subsequent reactivity of both 1-propanol and propylene glycol over Ni-Ir and Ni catalysts were followed by FTIR; C-C bond cleavage was found to occur at a lower temperature in propylene glycol than in 1-propanol

Design of two large coaxial cells for studying physical process using spatial TDR

This paper reports the design of two large coaxial cells for studying spatial distribution of state parameters during physical process using Spatial Time Domain Reflectometry (Spatial TDR). The first cell is designed to measure the spatial distribution of porosity during erosion. The main idea is to integrate in a large coaxial cell a water flow to induce erosion. The second cell is designed to study spatial distribution of water content during smouldering. The innovation here is to transform an existing smouldering reactor into a large coaxial cell for measuring the spatial distribution of the apparent dielectric permittivity. Both examples illustrate the versatility of electromagnetic measurement methods thanks to innovative cell design

Self-sustaining smouldering combustion of faeces as treatment and disinfection method

Smouldering combustion is a novel solution for sustainable treatment of waste. This is a low cost, off-grid and self-sustaining technology, that has been recently applied for soil remediation. Due to the high energy efficiency and the application scale, this technology is suitable for the treatment of organic waste with high moisture content (e.g. agricultural, manure, faeces). In addition, the temperatures achieved during smouldering combustion ensure pathogen destruction; therefore this technology is ideal to disinfect human waste. In this work, we present the study of the smouldering of faeces mixed with sand, at different reactor scales. Sand is used because smouldering needs a porous medium for the propagation of the reaction, enhancing oxygen diffusion. We investigated the limit of experimental parameters (moisture content, air velocity and sand-to-faeces mass ratio) that lead to the minimum faeces destruction rate in a self-sustaining process, using four different reactor sizes. It was found that there is a strong dependence on the moisture content limit with the reactor scale. On the other hand sand-to-faeces mass ratio and air velocity showed almost constant limit values. Experiments with mixed waste (faeces and agricultural) were also carried out to demonstrate the versatility and the robustness of this process towards the waste nature. Sand is clean and hot after the smouldering treatment. Part of the energy of the process can be recovered by mixing the hot sand to pre-dry a new batch of faeces. This can be repeated for at least five consecutive experiments

Investigation of self-sustaining smouldering of faeces: key parameters and scaling effects

The lack of adequate sanitation infrastructure within developing countries enables the transport of faecal matter containing harmful pathogenic compounds into the drinking water sources. The principal consequence of the pathogenic pollutant is 2.5 million preventable annual deaths. The utilisation of self-sustaining smouldering for the treatment of faecal matter mixed with sand is proposed as a solution as the high temperatures achieved ensure the destruction of the pathogens. Sand is used because it is low cost and it has been identified as an effective agent for increasing the porosity of fuels for application of smouldering treatments. Previous studies have shown the sustainability of smouldering combustion to be dependent upon experimental parameters such as moisture content, relative amount of sand and the airflow rate. In this work, we present the results of smouldering combustion experiments that were carried out to determine the sensitivity of the smouldering velocity to those experimental parameters. Experiments were conducted using four cylindrical reactors with varying size. To avoid variability, surrogate faeces which exhibits similar energetic, thermal, and mechanical properties to real faeces, are used in this study. Results showed moisture content is a critical parameter to control the sustainability of the process; however it has no effect on the smouldering velocity under robust conditions. The smouldering velocity showed a linear relationship with the air velocity and the faeces-to-sand mass ratio. Furthermore, it was demonstrated that these relationships are independent of scale. These results can be used to determine the reactor size and experimental conditions under realistic conditions