Hybrid sol-gel coatings for reducing wettability and storage degradation of biomass pellets

Long transport distances and extended storage of biomass pellets especially in humid environments provide a suitable setting for enhanced degradation in the form of moisture sorption, cracking and attrition. We developed an optically transparent, low-cost and environmentally friendly coating to reduce moisture sorption and storage degradation of pellets. The developed coating is a hybrid sol-gel, based on tetraethoxysilane (TEOS) and 3-gly-cidoxypropyl-trimethoxysilane (GPTMS) precursors. We coated two types of untreated and one type of torrefied wood pellets and stored them in a climate chamber during 1 month simulating a ship's hold, at a constant condition of 40 degrees C and 85% relative humidity. After 1 month of storage, the mean water contact angle increased by a factor of two compared to the uncoated ones. The lower wettability of the sol-gel coated untreated pellets compared to the non-coated torrefied pellets might provide an alternative to torrefaction.

Automated summary

Long transport distances and extended storage of biomass pellets can lead to degradation due to moisture sorption. We developed a low-cost and environmentally friendly coating to reduce this degradation. The coating, based on TEOS and GPTMS precursors, was applied to untreated and torrefied wood pellets and significantly increased the water contact angle after a month of storage in a humid environment.