The acidity of the different samples was evaluated by model ethanol dehydration reaction
. The reactions were performed in a fixed bed flow reactor, using 0.150 g of solid at 250[degrees]C.
(5) Dehydration reaction
takes place when orthosilicic acid absorbing much reaction heat, which reduces the reaction temperature tremendously and produces inorganic silica microspheres, the result verifies the results of Figs.
The type of acidity of ILs played a significant role in the efficiency of the dehydration reaction
. It was also found that the BrAlnsted-Lewis acidic sites of IL can selectively catalyze the protonation, dehydration, and deprotonation dehydrogenation in the reaction, and a synergetic effect of BrAlnsted and Lewis acid sites enhanced the catalytic performance of the IL.
assemblies (three) were designated with respect to the excess time given to each system after 2.5 h, as DCO-15, DCO-25, and DCO-35.
In the second step, the enamine A attack to aromatic aldehydes (addition reaction) to give intermediates B, which further undergoes dehydration reaction
to give 1,6-naphthyridine 3 (Step 3).
Compared with the dehydration of lactic acid in liquid phase or supercritical water, yield of acrylic acid was higher in gas phase dehydration reaction
(Odell et al., 1985; McCrackin and Lira, 1993).
For [gamma]-[Al.sub.2][O.sub.3] catalyst, the dehydration reaction
must be applied at higher temperature (400-450[degrees]C) to achieve high activity.
Although the first stage corresponds to dehydration reaction
, the second one corresponds to the thermal decomposition stage.
In the annealing process, the dissociative hydroxyl groups in the PVA chains go through dehydration reaction
resulting in more crystalline region.
At approximately 30 min of heating, the presence of dehydration reactions
(11) as well as reduction (12) and decarboxylation reactions (13) was observed.
Thus, a high heating rate provides a shorter time for the dehydration reactions
. Less water is lost at low temperatures; hence, more cellulose and lignin will be gasified with the promotion of moisture in the wood, which leads a lower yield of char.
Most of the monomers serve as building blocks that undergo iterative dehydration reactions
to generate mid-sized as well as long-chain polymers (several kilodaltons) that are proteins, DNA, RNA, carbohydrates, isoprenoids, and peptidoglycan (which makes up the cell wall).