Beta"-alumina incorporation

A patent describing a thermionic emitter for generating positive ions that incorporated a mixtnre of beta-alumina and inert material snch as charcoal positioned on a filament for heating the mixture has been issued. Two decades later, an alkali cation emitter, based on intercalated alkali ions in a graphite matrix, was proposed. When heated on a red hot filament, this source emits ions from alkali salts, which snbseqnently can be used to form product ions. 

The conventional amorphous silica-alumina catalysts have been substituted here by zeolites, especially of the H-ZSM-5 type [49J. Higher yields and higher pyridinc/p-picoline ratios arc obtained with zeolite catalysis. The micropores will reduce the formation of higher alkylated pyridines. The zeolites can be further improved by incorporating metal oxides (e.g. Pb, Tl, Co) or noble metals or by applying both types of promoters. As an example, a Pb-MFI catalyst, operated at 450 °C in a fixed bed reactor and fed with CH2 O/CH3CHO/NH3 in a 1.0 2.0 4.0 molar ratio gave 79 % total pyridines with a pyridine/p-picoline ratio of 7.5. Also zeolites MCM-22 and Beta [50] perform well in combined pyridine/p-picoline synthesis. 

When Ga203 is incorporated on a large pore hi silica-alumina zeolite, such as Beta, propane is also converted into aromatics, being in this case the selectivity much higher for the formation of naphthalene and methyl naphthalene than on Ga-ZSM-5 zeolite. Meanwhile, the Beta zeolite deactivates much faster (164). 

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