Continuous Flow Dehydrogenation of Isopropanol by Heterogenized Ir-POCOP Pincer Catalysts

Abstract

Supported Iridium pincer complexes were used to study gas-phase isopropanol
dehydrogenation under continuous flow system at temperatures 200-260 °C with different flow rates. First supported catalyst was [Ir(C2H4)(p-tBu2PO-tBu4POCOP)] supported by covalent bonding to silica, the second one was [Ir(HCl)(p-HO2C- tBu4POCOP)] supported by adsorption
to γ-Alumina. The highest activity of catalyst 1 was 11906 TON (TOF 1963 h-1) with 26% conversion and [Ir(C2H4)(p-tBu2PO-tBu4POCOP)] was supported by covalent bonding to silica
show higher activity and stability compare with catalyst 2 up to 24525 TON (TOF 3901 h-1)
with 90% conversion

Popular Abstract

The development of using transition metal in organic synthesis has had an important impact on organic synthesis and lead to the discovery of new reactions. Heck reaction who won the Noble prize stands as the prototypical example to illustrate how this field important in academia and industry. Catalyst is known as a substance that speeds up a chemical reaction but does not consumed by the reaction, and transition metal complexes have been used as a catalyst in many field such as pharmaconutrients, clean fuel and solar cell.

In general, an organometallic catalyst consists of two parts metal and ligand, the metal center bind to the ligand. The ligand is an organic or inorganic molecule attached to a metal atom by coordinate bonding, which is responsible for the electronic and steric properties of the organometallic catalyst, these complexes have been used as catalyst which highly efficient and has been employed in numerous industrial processes, Among the organometallic catalysts, the iridium metal group complexes have been used for dehydrogenation and transfer dehydrogenation reactions, dehydrogenation is a chemical reaction that involves the removal of hydrogen H2 from organic molecules and is the reverse of hydrogenation.

In this respect, alcohols dehydrogenation produces hydrogen, which is considered as an efficient energy carrier and has the highest energy content of any standard fuel by weight, also using hydrogen dramatically reduces pollution. Another benefit of alcohols dehydrogenation is produced aldehyde from primary alcohols and ketone from secondary alcohols, so dehydrogenation of alcohol yield carbonyl compounds, which are considered an important intermediate in organic synthesis. Another benefit is that alcohols dehydrogenation is known as a green oxidation procedure, which can minimize waste formation.

Iridium catalyst is considered an active catalyst for dehydrogenation of alcohols, so the thesis aimed to synthesized iridium catalyst and study dehydrogenation of isopropanol under continuous flow system, continuous flow process when the reactant and the product are charged and discharged simultaneously. Continuous flow processing is considered in crucial general feature in making the organic synthesis more economical and environmentally friendly resulted in a growing research area in both academic and industrial.

• author: Alharbi, Sabitan
• supervisor: Alexey Polukeev
• organization: Department of Chemistry
• course: KEMR32 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Chemistry
• keywords: Dehydrogenation, Iridium pincer complexes, Pincer catalyst, Inorganic chemistry, Oorganisk kemi
• language: English
• id: 8994117
• date added to LUP: 2019-09-12 15:35:44
• date last changed: 2019-09-12 15:35:44