Characterisation and evaluation of a commercial vanadia catalyst for ammoxidation of picolinest

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "dejavu="" sans";mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;="" mso-bidi-theme-font:minor-bidi;color:#00000a;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">A commercial 10 wt% V₂O₅/slsilicated <i><span style="font-size:11.0pt;line-height:115%;font-family:" calibri","sans-serif";="" mso-fareast-font-family:"dejavu="" sans";mso-bidi-font-family:mangal;color:#00000a;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">γ</span></i><span style="font-size:11.0pt;line-height:115%;font-family:" calibri","sans-serif";="" mso-ascii-theme-font:minor-latin;mso-fareast-font-family:"dejavu="" sans";="" mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;mso-bidi-theme-font:="" minor-bidi;color:#00000a;mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">-'alumina catalyst has been characterized by XRD, surface area measurement and chemisorption of oxygen and ammonia and evaluated for arnmoxidation of picolines from 200 to 330°C after reduction at 450°C in H₂ for 2 h. Chemisorption results indicate that vanadia is in a highly dispersed state in the catalyst and that temperature has promotional effect on O₂ uptake and detrimental effect on NH₃ uptake. Oxygen chemisorption seems to occur in oxygen vacancies created by reduction and NH₃ chemisorption seems to be structure sensitive on the catalyst at higher temperatures. The ammoxidation activity of the catalysts and yields of the nitriles increase with rise in reaction temperature up to 300°C and decrease with increase in feed rate above 2 cm^-3 h^-1. The catalyst exhibits the highest activity for ammoxidation of 4-picoline and the activity decreases in the order, 4-picoline > 3-picoline > 2-picoline. The activity results appear to correlate with the oxygen chemisorption capacities of the catalyst at different temperatures.</span></span>