Characterization of Mordenite-Supported Pd, Pt, and Ir Determined by CO Adsorption Microcalorimetry and the Dehydrogenation Reaction of C3 Alkanes

Abstract

Techniques such as adsorption microcalorimetry and the dehydrogenation of alkenes are used to measure the differential heats of adsorption and reactivity of several catalyst surfaces. An adsorption microcalorimeter built specifically to determine adsorption heats is employed. CO was used as the probe molecule in this study and was adsorbed on the following catalysts: Pd/mordenite, Pd-Pt/ mordenite, and Pd-Ir/mordenite. The results show that the differential heat of adsorption was between 50 and 150 kJ/ mol. The adsorption heat decreases with an increased in CO coverage for all catalysts. The best conversion for alkene studies was seen on the Pd-Ir/mordenite, which was close to 70%.

Microcalorimetric Study of the Catalytic Properties of SBA-15 Modified with Cu or Fe for Adsorption/oxidation of Methyl mercaptane

“…The differential heats of methyl mercapthan adsorption were measured using a Tian-Calvet heat flow microcalorimeter built in our laboratory 22,[33][34][35][36] . Before performing injections into the microcalorimetry cell where the catalysts were placed (Cu/SBA-15 and Fe/SBA-15), the catalysts were evacuated to 10 -6 Pa. Then, the microcalorimeter heat sink was subsequently raised around the cell and the system was allowed to equilibrate overnight.…”

“…Adsorption microcalorimetry has long been used in different areas of chemistry, but mainly in catalysis 22 . For example, many microcalorimetric studies have dealt with the adsorption of basic molecules (e.g.…”

“…Thus, it is often difficult to prepare clean metal surfaces and maintain them in a zero-valence state for microcalorimetry. New advances in adsorption microcalorimetry have made it possible to measure differential heats of adsorption on single metal crystals 22,23 , polycrystalline metal films 24,25 , and metal powders and metal based catalysts that are reactive towards oxygenates 26 . Microcalorimetry has been used effectively to probe sites on supported metal catalysts (e.g.…”

“…Pt/ SiO 2 ) that are not overly sensitive to poisoning by oxygenates. However, this sensitive technique has not yet been explored as a tool to determine the heats of adsorption/decomposition in situ on mesoporous solids, important data if you want to use a pilot plant employing solid catalyst beds for mesoporous decomposition reactions, because it is necessary to establish the amount of energy released during the process 22,27 .…”

Cluster-derived Ir–Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: a spectroscopic study

“…4 With this aim, bimetallic catalysts have shown good performances for many important reactions, such as hydrogenation of alkynes and dienes in olefins feedstock, 5 selective hydrogenation of unsaturated aldehydes, 6 preferential oxidation of CO, 7 hydrogen production 8 and light alkane dehydrogenation. [9][10][11][12][13] However, as shown in earlier studies, it has been a difficult task to understand the rationale behind a promotion effect of an inert metal on the catalytic behavior of a noble one. 14 For example, a relevant decrease in hydrogenolysis properties of a Group 8, 9 or 10 metal occurs when a Group 14 metal is added as a promoter.…”