b) providing {HEAD ~ the catalyst} to include {TAIL ~ at least one member} selected from the group consisting of chromium compounds, iron compounds, yttrium compounds, lanthanum compounds, cerium compounds, tungsten compounds, zirconium compounds, titanium compounds, vanadium compounds, phosphorous compounds, aluminum compounds, molybdenum compounds and amine compounds 
b ) providing { HEAD ~ the catalyst } to include { TAIL ~ at least one member } selected from the group consisting of chromium compounds , iron compounds , yttrium compounds , lanthanum compounds , cerium compounds , tungsten compounds , zirconium compounds , titanium compounds , vanadium compounds , phosphorous compounds , aluminum compounds , molybdenum compounds and amine compounds
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH