Heteropoly Acid For Isobutene Catalyzed Hydration Preparation Of Tert-butanol

There are large amount of n-butene and isobutene in mixed C4s and extracted C4s from refineries and rubber plant. With the expansion of the application fields of isobutene and tert.-butyl alcohol(TBA), a broad prospect is foreseen for the hydration of mixed C4s from isobutene to produce TBA. Recently, heteropoly acid catalysts were developed to solve the defects of hydration catalysts, such as low conversion, short service life, n-butene involved in reaction as well as isobutene liable to polymerization.For the first time, this paper makes a complete report of catalytic mechanism, process steps and pre-commercialization concerned with engineering scale-up experiments of isobutene catalytic hydration to produce TBA with heteropoly acid.Heteropoly acid with Keggin structure has catalytic hydration activity, which originates from its first order anion structure. When used in hydration reaction of isobutene, heteropoly acid has the advantages of high conversion, good selectivity and mild reaction conditions, etc.Under lab conditions, heteropoly acid catalysts were prepared.It was proven by industrial scale-up tests and extended tests that the catalyst preparation method has the characteristics of easy operation and good repeatability, so this method can be commercially applied in large scale.Self-prepared heteropoly acid solution was used to study various factors influencing catalytic hydration of isobutene in mixed C4s to produce TBA in a single lab reactor. It was found that the hydration of isobutene in mixed C4s to produce TBA is a reversible reaction, with heteropoly acid as the catalyst. Under single reactor conditions, this paper explored in detail the influences of reaction time, reaction temperature, agitating speed and water/oil ratio of the feed stream on the reaction results, and determines the optimal reaction conditions for TBA production from isobutene catalytic hydration. On the basis of detailed exploration of the operating conditions for isobutene hydration, a multi-stage reflux reactor was designed. Under optimized reaction conditions, the factory aimed target of isobutene conversion to be≥99.5% was reached for the first time in the multi-stage reflux continuous reactor.Considering the two possibilities of reaction control and transfer control that might exist in hydration reaction, parameter regression was used to treat the experimental data, obtaining reaction model 1 and reaction model 2 for isobutene hydration. Seen from the comparison of model calculation data and experimental data, it is regarded that the hydration reaction is of mass transfer control reaction, the kinetic formulation of isobutene catalytic hydration reaction was thus determined, expressed as the following: (?)The composition of TBA products from catalytic hydration of isobutene with heteropoly acid is rather complicated. Besides TBA, there are many kinds of C4s such as Sec.-butyl alcohol, isobutene, n-butene, isobutene and dimmers and trimers, as well as other derivatives, moreover, there is heteropoly acid catalyst that needs to be separated; therefore, it is hard to use mathematic model to fulfill the optimal calculation of TBA separation and rectification. It was found by the schedule of bench scale experimental data combined with optimized condition that:①The operating pressure variation doesn't affect the composition of TBA-water azeotrope.②Rectification operation must be kept under lower pressure (or higher vacuum), and the suitable operating temperature is≤60℃It is hard to condense tower top products with industrial ambient temperature cooling water.③In order to meet for the requirement of top tower product separation (TBA content to be≥85% of the top tower products, and≤0.5% of the products in the tower), the tower plate number should be 11 in theory; the minimum reflux ratio should be 5, suitable reflux ratio should be 10; and the actual plate number is 32.④It is shown by water scrubbing equilibrium data that the partition coefficient of TBA in water/oil phase is 2 in average in the remaining C4 system after water scrubbing.⑤In order to obtain the stipulated water scrubbing effect to keep the...