A Catalyst for Photocatalytic Conversion of Acetylene to Ethylene

NU 2022-223

INVENTORS

Aaron E. Stone

Francesca Arcudi

Luka Dordevic

Emily A. Weiss

Joseph T. Hupp*

Samuel Stupp

SHORT DESCRIPTION

A new and improved catalyst that enables the photocatalytic conversion of acetylene to ethylene.

BACKGROUND

Ethylene (C2H4) holds a pivotal role as an intermediate in 50–60% of global plastics production, derived predominantly from the steam cracking of petroleum. However, this process introduces impurities, particularly acetylene, posing a significant challenge for ethylene polymerization. To obtain polymer-grade ethylene essential for plastics manufacturing, the acetylene concentration in crude ethylene streams must be reduced to a few parts per million. The existing state-of-the-art technology involves thermocatalytic hydrogenation of acetylene, but it faces issues like high energy input, reliance on excess H2 gas, and the use of costly precious metal Pd as a catalyst.

ABSTRACT

Northwestern researchers have pioneered a distinctive method to convert stray acetylene, a potential contaminant in plastic production, directly into ethylene, addressing environmental concerns associated with prevailing purification systems. The technology utilizes a photocatalytic approach, designing a catalyst based on MOFs known for their stability, crystallinity, and high surface area. Incorporating a photosensitizer enables the catalyst to trigger a photo-sensitive reaction using visible light, presenting a more sustainable strategy. This innovative technology demonstrates superior selectivity and efficiency in milder conditions than the industry standard. The selective photocatalytic semihydrogenation, powered by visible light and conducted at room temperature, utilizes a MOF catalyst incorporating cobalt-porphyrins. Under industrially relevant conditions of the photocatalytic mixture, the system achieves nearly 100% conversion of acetylene to ethylene with over 99.9% ethylene selectivity, providing a sustainable alternative while surpassing the efficiency of other ethylene purification strategies.

APPLICATIONS