Calorimetric Adsorption for Catalyst Characterisation

A Hiden Customer, Dr Rob Brown from the University of Huddersfield, reviews his research undertaken using the Hiden HPR-20 QIC Real time Gas Analyser in Labmate UK & Ireland : focus on Mass Spectrometry magazine.

HPR-20 QIC

Many processes in fine chemicals manufacture rely on acid or base catalysis. Traditional homogeneous acids and bases, such as sulphuric acid and caustic solutions lead to large amounts of contaminated waste on separation from reaction mixtures. The use of solid catalysts would eliminate this waste, but offer challenges in terms of providing adequate catalytic activity.

Crucial to the development of sufficiently active solid acids and bases are catalyst characterisation techniques which can help us understand structure/function relationships.

The most widely used approach is to introduce the probe gas from a gas burette, allowing the system to reach equilibrium at each addition, and progressively increasing the pressure of the gas.

We have developed a different approach, in which the catalyst sample (< 50 mg) is held on a frit in a flow-through differential calorimeter and the probe gas is introduced as a series of pulses injected into a steady flow of carrier gas, normally nitrogen.   The pulses are delivered from a gas sampling valve upstream of the calorimeter under automatic control. The pulse size is controlled by the sampling loop, and by the make-up of the pulse gas (which is typically 1% probe gas in the inert carrier).  Again, the calorimeter is held at a temperature to minimise weak adsorption on non-active sites in the catalyst. The outflow from the calorimeter cell is sampled by a low-flow capillary interface linked to a Hiden HPR-20 QIC Quadrupole Mass Spectrometer…” Read full article

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Paper Reference:
E. Andrijanto, E. A. Dawson, D. R. Brown (2012) “Hypercrosslinked polystyrene sulphonic acid catalysts for the esterification of free fatty acids in biodiesel synthesis” Applied Catalysis B: Environmental 115-116, Pages 261-268