Continuous Production of Methyl Lactate from Hemicellulosic Sugars: Identifying and Sorting out Sn-USY-Based Catalyst...

Area of Science:

• Catalysis
• Materials Science
• Biomass Conversion

Background:

• Zeolites are crucial in catalytic processes.
• Tin-functionalized zeolites offer unique catalytic properties.
• Biomass conversion to valuable chemicals faces challenges like catalyst deactivation.

Purpose of the Study:

• To investigate the catalytic performance of potassium-exchanged tin-functionalized USY zeolite ([K]-Sn-USY) for methyl lactate production.
• To understand and mitigate deactivation mechanisms of the [K]-Sn-USY catalyst.
• To evaluate the catalyst's stability and efficiency with various carbohydrate feedstocks.

Main Methods:

• Continuous transformation of glucose, xylose, and their mixtures using [K]-Sn-USY in a fixed-bed reactor at 150 °C.
• Analysis of catalyst deactivation causes, including potassium leaching and organic deposition.
• Addition of small amounts of potassium (KCl or KOH) to assess its effect on catalyst stability.

Main Results:

• The [K]-Sn-USY catalyst efficiently converts glucose and xylose to methyl lactate.
• Catalyst deactivation was observed, primarily due to potassium leaching and furanic deposition, especially with hexoses.
• Addition of 10 mg/kg potassium significantly alleviated deactivation, enabling stable production.

Conclusions:

• Potassium addition is an effective strategy to enhance the long-term stability of [K]-Sn-USY catalysts.
• The stabilized catalyst achieves over 30% methyl lactate yield for more than 140 hours.
• This approach enables efficient methyl lactate production from both individual sugars and complex biomass hydrolysates.