Study of Dry Reforming Of Biogas for the Production of Syngas

Abstract

The increasing changes in the behaviour of our atmosphere are due to rapid release of combustion products from fossil fuels. As the demand for energy is growing globally, these changes can be expected to escalate unless alternate energy sources are made available. Among various energy sources that can substitute fossil fuels, biogas appears as the option with highest general global potential. Feed stocks like municipal waste, food waste, sewage, animal manure, liquid industrial byproducts and some crop waste are available in abundance which can be utilized for the production of biogas. One of the issues related with biogas is the amount of CO2 content which lowers its average calorific value and adiabatic flame temperature. Thus, usage of the biogas as an effective energy source can be achieved using various conversion technologies like catalytic reforming to convert it in to a useful form such as syngas.

Dry reforming of biogas in a reforming reactor generates syngas which possesses better combustion properties when compared to biogas. Catalyst employed in reforming process plays an important role in enhancing the conversion of biogas in to syngas. In the present work, dry reforming of biogas was carried out in a tubular type fixed-bed down-flow reactor under atmospheric pressure. Nickel based catalyst were prepared and tested in the reforming process. Effect of alumina support and calcium promoter on activity and stability of Ni catalyst was also analyzed in the current work.

Catalysts were synthesised using impregnation method and characterised by XRD, SEM, EDS and CHNS techniques. The effect of the temperature on the catalytic performance was analyzed in the temperature range of 700°C to 900°C.The reforming results inferred that addition of Al2O3 support increased the catalytic activity but addition of CaO promoter has less impact in the activity of the catalyst. However, CHNS results showed inhibition of carbon deposits in promoted catalyst. Maximum conversions of CH4 and CO2 achieved for 10%Ni-15%Ca/Al2O3 catalyst were 84.9 and 98.1% respectively, with maximum hydrogen yield of 40.6% with a H2/CO ratio of 1.06 Experiments were carried out to compare fuels available for C.I. engine operation such as diesel and palm oil biodiesel blends. Their performance was then compared with the data of syngas based dual fuel CI engine operations available in various literatures. Palm oil biodiesel was prepared using trans-esterification of crude palm oil using KOH catalyst. Usage of biodiesel blends (B20, B10) helped in achieving 10-15 % of diesel substitution in providing the similar energy where as syngas dual fuel operation helps in achieving a diesel substitution of about 60% at higher loading conditions [70]. Both bio-diesel and syngas in dual fuel operation with diesel reduce NOx emissions when compared to neat diesel operation.