Integral conversion of SO2: Hysteresis and rate discontinuities

Abstract

AbstractThe oxidation of SO2 was carried out over an American Cyanamid V2O5 catalyst in an insulated integral reactor without significant interparticle resistances under the following conditions: 10 percent SO2‐air feed, feed temperatures in the range of 430°C to 590°C, 108 kPa pressure, and entrance temperatures of the gases in the annular heat exchanger from 400°C to 450°C, with one set of conversions being obtained without annular air flow. Gas analysis was accomplished by the oxidation of SO2 to SO3 with potassium permanganate. The method was fully tested before adoption. Final conversions in the range of 5 to 60 percent were observed. A hysteresis loop was found in the plane of outlet conversion versus the average feed temperature. The multiplicity is possibly stable but probably decays with the time constants in the order of days which is evident from the transient data that were obtained. A one dimensional model was able to correlate the conversion data through the Arrhenius rate parameters in the Boreskov‐Sokolova(8) rate expression which changed from A = 1.92 × 107 m3/(s·kg) and E = 151 MJ/kmol to A = 0.344 m3/(s·kg) and E = 33.5 MJ/kmol at a calculated temperature at the surface of the catalyst of 517°C. Similar behavior has been observed in other studies concerned with basic kinetic studies over catalyst pellets. The analogy between the behavior of the catalyst pellets and the behavior of the integral reactor can thus be fully drawn with respect to hysteresis and rate discontinuities.