Catalysis of Organic..

3422,5-Dimethyl-2,4-Hexadiene10086Yield83778055 57604020Granosil 750 JF20/50 LVMAttagel 40Mega Dry36K 306FTonsil 610 G0Figure 5. Catalytic activity in the optimized screening tests. (Cat. = 9 g ofMega Dry clay; T = 290 °C; P = 0.1 MPa; Feed = 2.8 M DMED/CH 3 OHsolution in N 2 flow; LHSV = 0.92 h -1 ).performances than both the previously patented montmorillonite clay catalyst (K306 F) (12) and a pure attapulgite clay (Attagel 40). Compared tomontmorillonite, attapulgite has a higher surface area and pore volume, but lowerswelling capacity; therefore, it may be suggested that commercial mixtures of thetwo clays represent the best compromise for the reaction studied, because eachacid-catalyzed reaction and substrate has specific requirements, as previouslyshown in both the acylation reactions with acid treated clay F20 (26) and thevapour-phase Fries rearrangement with T-4480 zeolite (27, 28). Both Granosil 750JF and Mega Dry showed significantly better higher and more constant catalyticperformances, up to 400 h of time-on-stream, than those of pure attapulgite(Attagel 40) (Fig. 6). Lastly, it must be noted that Granosil 750 JF is an ISO-2002certified product (23), while the physical properties of Mega Dry, which is notcertified, are kept constant during production. Thus, constant performances arewarranted for both catalysts.We investigated the possibility of regenerating the two most interestingcatalysts - after an accelerated deactivation achieved feeding a DMED-richsolution at high LHSV value - by heating at 550 °C for 4.5 h, under a N 2 /air flow.