کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
43692 45983 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Study of the citral/acetone reaction on MgyAlOx oxides: Effect of the chemical composition on catalyst activity, selectivity and stability
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Study of the citral/acetone reaction on MgyAlOx oxides: Effect of the chemical composition on catalyst activity, selectivity and stability
چکیده انگلیسی

The liquid-phase citral/acetone reaction was studied on MgO, Al2O3 and MgyAlOx mixed oxides with Mg/Al molar ratios of 0.11–3. The density, strength and nature of surface acid sites were determined by NH3 thermodesorption and FTIR of pyridine. The surface basic properties were probed by temperature-programmed desorption of CO2. The rate of the citral/acetone cross-aldolization to pseudoionones increased linearly with the density of strong O2− base sites. Thus, the pseudoionone synthesis was efficiently promoted on MgO and Mg-rich MgyAlOx samples. In contrast, the initial rate of the parallel acetone self-condensation reaction increased with the density of Lewis acid sites, and diacetone alcohol was more rapidly formed on Al2O3 and Al-rich MgyAlOx samples. Differences in the reactant adsorption strength on surface Al3+ sites may explain the observed differences between the acid-catalyzed mechanisms of cross- and self-aldolization reactions. In situ catalyst deactivation was determined by performing two consecutive catalytic runs. The activity decay of MgyAlOx samples during the citral/acetone reaction was between 15 and 20%, irrespective of the catalyst composition.

The liquid-phase citral/acetone reaction was studied on MgO, Al2O3 and MgyAlOx mixed oxides. The rate of the citral/acetone cross-aldolization to pseudoionones increased linearly with the density of strong O2− base sites. In contrast, the initial rate of the parallel acetone self-condensation reaction augmented with the density of Lewis acid sites.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Catalysis A: General - Volume 345, Issue 2, 1 August 2008, Pages 143–151
نویسندگان
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