Catalytic Conversion of Bioethanol and Acetaldehyde to Butadiene Over a Tantalum Oxide-Supported Spherical Mesoporous Silica Catalyst in a Circulating Fluidized Bed

Spherical silicas with mesopore (6 nm) supported tantalum oxide samples (Ta/SMS) were prepared with the impregnation method using different Ta loading amounts for the production of 1,3-butadiene (BD) from ethanol and acetaldehyde (ethanol to BD, ETB). To obtain the optimum Ta loading amount, the Ta/SMS catalysts were first tested in a fixed-bed reactor. The characteristics of the Ta/SMS catalyst was analyzed by scanning electron microscopy, inductively coupled plasma atomic emission spectrometry, and N-2 physisorption analysis. Before testing the catalyst in a hot-bed circulating fluidized bed (CFB) reactor, the mechanical strength and hydrodynamic properties of the Ta/SMS catalyst were examined by using the attrition test and a cold-bed CFB reactor, respectively. The catalytic results in the hot-bed CFB reactor revealed that the Ta/SMS catalyst had a different catalytic performance for production BD, which could be attribution to the feed concentration and circulation rate of catalyst. The hot-bed CFB test for ETB with the Ta/SMS catalyst was stably operated for 140 h, and an average conversion of 56.7% and BD selectivity of 70.5% were obtained.