Preparation of Mesoporous Alumina Particles by Spray Pyrolysis and Application to Double Bond Migration of 2-Butene

Abstract

The objective of the present study is to investigate the catalytic performance of mesoporous alumina that were prepared via spray pyrolysis for double bond migration from 2-butene to 1-butene. The mesoporous alumina particles were prepared via spray pyrolysis by changing the types of organic surfactants and Al precursors. The texture and acidic properties of mesoporous alumina were analyzed through N2 adsorption, SEM, ammonia-temperature programmed desorption, and FT-IR of adsorbed pyridine. The morphologies and texture properties of the mesoporous alumina were found to have been strongly influenced by the combination of the Al precursor and the structure-directing agents. The mesoporous alumina samples had two kinds of acidic sites: a Lewis acid site and a H-bonded weak acid site. 1-Butene was produced selectively through double bond migration of 2-butene over all of the mesoporous alumina catalysts. The catalyst prepared by using a chloride compound as an aluminium precursor and CTAC as a structure-directing agent showed the highest activity in the double bond migration of 2-butene, which was attributed to its large surface area and an overall high amount of acid sites.

Alumina with Various Pore Structures Prepared by Spray Pyrolysis of Inorganic Aluminum Precursors

“…Alumina has abundant applications in the ceramics industry and heterogeneous catalysis and has been widely used as absorbents, abrasive materials, and biomaterials. − The application of alumina depends greatly on its properties, such as surface area, morphology, porosity, and so on. To fulfill the requirements in different fields, alumina with different surface areas (50–700 m 2 ·g –1 ), morphologies (e.g., spherical, nanorod, or irregular), particle sizes (nanometers to micrometers), phase compositions (γ, κ, θ, η, or α phase), and microstructures (e.g., mesoporous or microporous structure) can be produced. ,− Among these properties, the pore structure is one of the most important because most catalysts based on mesostructured alumina exhibit excellent catalytic activity . For conventional alumina with uncontrolled porosity, deactivation could be induced by coking and plugging, consequently hindering the diffusion of reactants and products. , For instance, mesoporous alumina-supported Re 2 O 7 catalysts give rise to a 3-fold higher conversion activity in the self-metathesis of 1-hexene than the same catalysts supported on γ-Al 2 O 3 without a uniform pore structure .…”

“…For instance, mesoporous alumina can be prepared by the spray pyrolysis of Al(NO 3 ) 2 ·9H 2 O in the presence of the surfactants cetyltrimethylammonium bromide (CTAB) and urea . Additionally, Song et al prepared mesoporous alumina particles using spray pyrolysis by changing the types of organic surfactants and Al precursors. It should be noticed that the formation of mesostructures in these works was attributed to the use of structure-directing reagents.…”

“…It should be noticed that the formation of mesostructures in these works was attributed to the use of structure-directing reagents. The obtained morphologies and structural properties (surface areas, pore volumes, pore size distributions) were strongly influenced by the templating agents. , …”