Highly Efficient Low-loaded PdO_x/AlSiO_x Catalyst for Ethylene Dimerization.

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Ethylene dimerization is a key industrial process.
• Current methods rely on homogeneous catalysts, which present separation and environmental challenges.
• There is a need for more efficient and sustainable catalytic systems.

Purpose of the Study:

• To develop a highly active and selective heterogeneous catalyst for ethylene dimerization.
• To understand the fundamental mechanisms underlying the catalytic activity.
• To integrate the dimerization catalyst with a metathesis catalyst for sequential reactions.

Main Methods:

• Synthesis of a heterogeneous catalyst with atomically dispersed palladium (Pd).
• Ethylene dimerization reaction studies under industrially relevant conditions.
• Kinetic experiments, catalyst characterization (e.g., spectroscopy, microscopy), and density functional theory (DFT) calculations.
• Integration of the Pd catalyst with a molybdenum (Mo)-containing olefin metathesis catalyst in a single reactor.

Main Results:

• The developed heterogeneous Pd catalyst demonstrated high activity and selectivity for ethylene dimerization, outperforming existing catalysts.
• Achieved 80% selectivity to C4-hydrocarbons at 42% ethylene conversion at 200°C.
• DFT calculations and characterization provided insights into the active sites (isolated Pd(II)Ox species).
• Integrated system achieved 98% selectivity to propylene via sequential dimerization and metathesis.

Conclusions:

• Atomically dispersed Pd on a heterogeneous support is a highly effective catalyst for ethylene dimerization.
• The catalyst operates without co-catalysts or activators, simplifying the process.
• The integrated system enables efficient co-production of propylene from ethylene.