De Nooijer, Niek (PhD)
Biogas to hydrogen in a fluidized bed membrane reactor
The increasing demand over the last decades for reduction of greenhouse gas (GHG) emissions and reducing the exploitation of fossil fuels has given rise to the development of new technologies and alternative energy carriers. Hydrogen is one of the high potential energy carriers. Currently, hydrogen is widely used in the chemical industry, in food processing and in the production of ammonia and methanol, among others. The conventional method for hydrogen production is through the use of steam methane reforming producing significant GHG emissions. The increasing demand for hydrogen and the potential for hydrogen in the energy system puts the emphasis on the development of a sustainable process for the production of hydrogen, and in particular from a renewable source.
Biogas is one of the renewables that could be utilized as alternative for natural gas in the production of hydrogen. Biogas is produced from biomass mainly through digestion of organic substrates (manure, sewage sludge, organic fractions of industry waste and energy crops. The different feedstocks for biogas production results in many different biogas compositions. Where the gas composition mainly consist out of CO2 and Methane with traces of other gasses such as H2, O2, N2, CO, H2O H2S.
In this project the concept of a fluidized bed Membrane reactor (FBMR) is used to produce hydrogen from biogas. The hydrogen produced during the reaction will be selectively removed through Pd-based membranes consequently shifting the thermodynamic equilibrium of the process towards the products. A pure stream of hydrogen is obtained removing the necessity of downstream process. Furthermore, due to the shift effect the reactions can be carried out at lower temperatures.
The performance of the FBMR for different biogas compositions will be studied experimentally, including the influence of hydrogen sulfide on the membrane performance, as well as computationally. A phenomenological model for the FBMR will be further developed through a more fundamental study, in particular assessing the validity of often applied assumptions. The hydrodynamics and mass transfer phenomena in fluidized bed membrane reactors will be studied simultaneously, combining Particle Image Velocimetry with Digital Image Analysis using high-speed camera’s in the visual and infra-red wavelengths, which enables measuring the instantaneous particle hold-up and solids mass flux profiles and gas phase concentration profiles in the dilute regions of the pseudo-2D bed. The experimental study is continued for high-temperature and reactive conditions using endoscopic PIV. A list of objectives is represented below.