Section 1065.1117 - Reactor aging cycle for determination of vanadium sublimation temperatureThis section describes the conditions and process required to operate the reactor described in § 1065.1115 for collection of the vanadium sublimation samples for determination of vanadium sublimation temperature. The reactor aging cycle constitutes the process of testing the catalyst sample over all the test conditions described in paragraph (b) of this section.
(a) Set up the reactor to flow gases with a space velocity of at least 35,000/hr with a pressure drop across the catalyst and capture beds less than 35 kPa. Use test gases meeting the following specifications, noting that not all gases will be used at the same time:(1) 5 vol% O2, balance N2.(2) NO, balance N2. Use an NO concentration of (200 to 500) ppm.(3) NH3, balance N2. Use an NH3 concentration of (200 to 500) ppm.(b) Perform testing as follows:(1) Add a new catalyst sample and capture bed into the reactor as described in § 1065.1113 . Heat the reactor to 550 °C while flowing the oxygen blend specified in paragraph (a)(1) of this section as a pretest gas mixture. Ensure that no H2O is added to the pretest gas mixture to reduce the risk of sintering and vanadium sublimation.(2) Start testing at a temperature that is lower than the point at which vanadium starts to sublime. Start testing when the reactor reaches 550 °C unless testing supports a lower starting temperature. Once the reactor reaches the starting temperature and the catalyst has been equilibrated to the reactor temperature, flow NO and NH3 test gases for 18 hours with a nominal H2O content of 5 volume percent. If an initial starting temperature of 550 °C results in vanadium sublimation, you may retest using a new catalyst sample and a lower initial starting temperature.(3) After 18 hours of exposure, flow the pretest oxygen blend as specified in paragraph (b)(1) of this section and allow the reactor to cool down to room temperature.(4) Analyze the sample as described in § 1065.1121 .(5) Repeat the testing in paragraphs (b)(1) through (4) of this section by raising the reactor temperature in increments of 50 °C up to the temperature at which vanadium sublimation begins.(6) Once sublimation has been detected, repeat the testing in paragraphs (b)(1) through (4) of this section by decreasing the reactor temperature in increments of 25 °C until the vanadium concentration falls below the sublimation threshold.(7) Repeat the testing in paragraphs (b)(1) through (6) of this section with a nominal H2O concentration of 10 volume percent or the maximum water concentration expected at the standard.(8) You may optionally test in a manner other than testing a single catalyst formulation in series across all test temperatures. For example, you may test additional samples at the same reactor temperature before moving on to the next temperature.(c) The effective sublimation temperature for the tested catalyst is the lowest reactor temperature determined in paragraph (b) of this section below which vanadium emissions are less than the method detection limit.