Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

Laboratory experimentsPP-III-22Studies were carried out on the influence of methanol concentration and temperature ofthe gas flow entering the adiabatic reactor on the operation efficiency of the adiabatic layer ata space velocity of the gas flow of 6000, 8000, 14000 and 24000 h –1 . Analyzing the resultspresented we can conclude that the influence of the temperature, methanol concentration andspace velocity of the feed gas entering the adiabatic layer on the total methanol oxidation andselectivity of the process is complex. Methanol concentration and space velocity are the mostimportant factors. Their increase leads to rapid decrease of the borders of applicability of theadiabatic layer. Temperature influence is limited by the operating conditions of the mainreactor. At low inlet temperatures the limiting factor is methanol conversion, while at highertemperatures the selectivity is more important.Industrial experimentA fifteen months’ industrial experiment was carried out. The industrial installationmonitored consists of two pseudo-isothermal reactors. An adiabatic layer with a thickness of50 – 60 mm was located under the reactors.Mössbauer spectrometry, XRD and chemical analysis were used to characterize fresh andpost reaction iron molybdate catalyst. Catalytic measurements were performed too. Nodifferences were found between sample of fresh catalyst and samples discharged from theadiabatic layer.Conclusions1. Using an adiabatic layer under the main reactor leads in all cases to a loss offormaldehyde due to its secondary oxidation to CO. Carefully controlling the processparameters allows full compensation of these losses by the oxidation of the methanolentering from the main reactor and the secondary oxidation of DME, mainly toformaldehyde.2. The results from the Mössbauer spectroscopy, XRD and the chemical analyses reveal noirreversible change in the chemical and phase content of the catalyst. The catalyticproperties of the catalyst used in the adiabatic layer remain virtually unchanged.AcknowledgementThis work is supported by Bulgarian Ministry of Education, Project VU- X-305/07.References1. Ana Paula Vieira Soares, Manuel Farinha Portela, Alain Kiennemann, Catal. Rev. 47 (2004) 125.2. G. Sioli, EP 1 166 864 A1, (2002).3. K. Ivanov, BG patent No 60779 B1 (1993).345