Abstract: Gas streams flowing in a nitrile synthesis plant, and particularly the hot reactor effluent gases, are analyzed by a new method wherein sample gas streams are filtered and temperature conditioned in the range from about 350.degree. to about 450.degree.F. before being passed to a gas analyzer instrument, preferably a mass spectrometer. With the latter instrument the conditioned stream of gas is passed continuously through the ion source assembly throughout the mass scan period, a mode of operation which assists in reducing lag in analysis to very little more than gas transit times. The mass spectrometer generates peaked direct current electrical signals which can be peak detected and amplified in a linear fashion to drive a direct-reading recorder instrument or such signals can be interfaced with a digital computer for programmed computation and readout of gas stream composition.

Abstract: The synthesis of nitriles such as acrylonitrile by the ammoxidation of mixtures of an olefin such as propylene or isobutylene, ammonia and oxygen or air is operated out low molar feed ratios of ammonia: olefin in the range of 1.03 to 1.07:1 and high excess oxygen levels of 4 to 7 mol % in the reactor effluent gases without significant losses in nitrile yield or significantly increased levels of oxygenated by-products. Control under such conditions is effected by analyzing the reactor effluent gases, previously temperature-conditioned at 350.degree. to 450.degree. F and solids removed, by a mass spectrometer instrument operating in a closed gas sampling and conditioning circuit or loop outside the reactor, and adjucting the input feed gas mixture in response to said effluent gas analysis to maintain the prescribed low ammonia rate in the feed and the excess oxygen level in the effluent gases leaving the reactor.