Energy production from biomass
Mehri Sanati, School of Technology and Design/Chemistry

1. Physical and Chemical Characterisation of emitted submicron aerosol particles from biomass gasification boiler: In Sweden bio-fuels including peat constitute one of the major energy sources contributing to approximately 16% (97 TWh) of the total energy supply, and increasing by approximately 3 TWh annually (Administration 2001). There are a growing number of medium sized heating units (0.5-10 MW) operating on wood-based biofuels, using combustion technique. Biomass gasification technique could be also used for production of heat and electricity or uppgrading of product gas from the boiler. In the later case, objective of the project is to develop a process to produce a clean hydrogen rich gas (an intermediate product for the production of commercial quality hydrogen, vehicle fuel and others) as a first step towards a new renewable, affordable and clean energy carrier both for stationary and transport applications. Characterisation of emitted particle will be performed in biomass gasification system in order to design an optimal cleaning devices.

2. Investigation of catalytic deactivation by deposition of submiron particle (inorganic compounds) Catalytic steam reforming will be used for uppgrading of gasify product from biomass gasification system. The catalyst will be deactivated by exposure to emitted particles from gasification system. In this project the emitted particles will be physically and chemically characterised. The performance of catalyst will be examined in steam reforming process. The both above mentioned projects consists of research and development activities (including the initial validation of technical and economic feasibility in a pilot plant especially equipped for this purpose and at considerable scale), research related networking activities, training activities and dissemination activities. A long-term objective is synthesis gas production for synthetic vehicle fuels on the basis of the renewable energy sources. The project is a EU-project, to demonstrate the conversion of a solid biofuel into a medium calorific value gas by gasification at elevated pressure using a steam and oxygen mixture.

3. Application of Aerosol Technology in production of NOx-sensor (detection of nitrogen oxide): The goal of the project To develop aerosol technology methods to synthesize nanoparticles of catalytic active materials (metal / oxide) to be used in gas sensitive field effect sensors. To correlate particle size with gas sensor properties like sensitivity and response time to different gases. To correlate particle size and penetration depth of the metal to deactivation phenomena of the sensors. The goal is an essentially improved sensor technology regarding long term stability at high temperature and in corrosive environment, and an considerably improved selectivity to a large number of gases in car exhaust and flue gases from boilers. This will greatly improve the possibility to reduce fuel consumption and emissions from cars and boilers. The term aerosol has been used to describe small particles (solid or liquid) suspended in a gas, where the particle size range from nanometer scale to roughly 100 micrometers. The industrial routes for production of varieties of material such as, metals, semiconductor, nonoxide ceramic, metal oxide, polymers, and composites were developed long before the basic science and engineering of aerosols were understood. The aerosol methods for the generating of materials have been developed to meet the need for producing particles and films with controlled composition and particles with a controlled size distribution and other properties that cannot be obtained by alternative routes. These routes to producing materials exploit aerosols solid or liquid particles in gases to make films and powders with special characteristic. The technology is based on field effect transistor devices with catalytic metals at the gate material, Gases, which react with the catalytic metal will change the current through the transistor. Silicon carbide as the semiconductor in these devices has the advantage of being a very inert and chemically resistant material, which stays as a seminconductor even at very high temperatures (> 1000°C). Material quality and processing methods are today mature enough for commercialization of SiC based devices. AppliedSensor, Linköping, has started to commercialize a SiC component for detection of NH3 / NOx in diesel exhausts to control the injection of urea, which produces ammonia, in the SCR (selective catalytic reduction) system where ammonia reacts with NOx in the catalytic converter and nitrogen gas and water is formed. Up till now catalytic metals has been used as the gate material in the SiC sensor devices. However, we know that both the metal and the insulator at the metal -insulator interface take active part in the gas detection mechanism. For example for the detection of ammonia the number of triple points of gas / metal / oxide is crucial for the gas sensitivity. A way to use this knowledge is to instead deposition of metal onto a smooth insulator surface use metal impregnated oxide particles. This will increase the number of triple points considerably. Furthermore, the selectivity of the sensors depends on the combination of metal and insulator as well as the operation temperature. The possibility to use the aerosols to synthesize particles in this project increases the number of available gate materials considerably. It is also likely that the particle size in itself will influence sensor parameters like selectivity and speed of response. A problem with operation of the sensor devices in corrosive environment is restructuring of the catalytic metals. There is a considerable chance that this will be prevented when the catalytic metal is stabilized by the particle matrix. This is the background for the development of particles produced by the aerosol technology to be used as gate material in field effect sensor devices in this joint project between Växjö and Linköping Universities. The method in this project is cross disciplinary and ties together unique national competences: · S-SENCE, Swedish Sensor Center, at Linköping University, center of excellence with long experience, large competence and excellent equipment in the field of sensors and sensor systems, which are developed in projects together with industrial partners. · The institut for Bioscience and Process technology, Växjö University, which participates in 3 research schools within aerosol science and technology, has a large international network within this area and industrial co-operation with catalyst producing companies.