“…Reduction of tar formation can be achieved by different ways such as varying the operating conditions, adding catalysts to the feedstock, mechanical cleaning of cold gas and using secondary catalytic bed to decompose tar into gas products (Anisa et al, 2011). In the case of using secondary catalytic bed, many type of catalysts were studied (Hu et al, 2006;Florin and Harris, 2008;Kimure et al, 2006). Iron based catalysts are widely used to decompose of tar (Min et al, 2011;Uddin et al 2008;Khelfa et al, 2009;Hurley et al, 2012;Xie et al, 2009;Tang et al, 2010;Xiwei et al, 2012).…”