Fabrication and characterization of a microreactor made of Pd-loaded carbonized tracheids thin plates (CTP)

Abstract

We found that a carbonized tracheids thin plate (CTP) with a thickness of less than 1 mm functions as a bundle of microfluidic channels (20 × 10 μm rectangular). By stacking CTPs, we can create microreactors of varying shapes and lengths. The water penetration rate of tracheids increased from near-zero to 59.1 % when the thickness of CTP decreased from 2 mm to 1 mm, and the light transmission significantly increased as well. Moreover, with a thickness of 0.5 mm, the water penetration rate rose to 72.3 %, emphasizing the importance of thickness for using tracheids as microfluidic channels. While previous reports have mentioned thin carbonized softwood plates, none have substantiated their effectiveness in liquid transport systems. We fabricated a reactor consisting of 150 CTP disks (φ5 mm, t = 0.75 mm) with Pd nanoparticles loaded inside tracheids for catalytic reactions. After a single pass, 75 % conversion rate was obtained in the reduction of p-nitrophenol to p-aminophenol, confirming the catalytic reaction in CTPs. In comparison to a commercially available column filled with Pd/C particles, CTP is expected to have a larger effective surface area (≈6.7 times). CTP has a high heat generation capacity and can withstand temperatures exceeding 450 °C, making it highly functional as a microreactor. The CTP reactor facilitates the transport of both polar and non-polar solvents. CTP technology is more optimal for softwood internal structures than hardwoods. This novel technology offers cost-effective and environmentally friendly material suitable for a wide range of applications.