Valorization of Napier grass via intermediate pyrolysis: Optimization using response surface methodology and pyrolysis products characterization

Abstract

This study presents first optimization report on pyrolysis oil derived from Napier grass. Effects of temperature, heating rate and nitrogen flow rate on the intermediate pyrolysis of Napier grass biomass in a vertical fixed-bed tubular reactor were investigated collectively. Response surface methodology with central composite design was used for modelling the process and optimization of the process variables. Individual second order polynomial model was found to be adequate in predicting bio-oil, bio-char and non-condensable gas yield. The optimum bio-oil yield of 50.57 wt% was recorded at 600 o C, 50 o C/min and 5 L/min nitrogen flow. The bio-oil obtained throughout this study was two-phase liquid, organic and aqueous phase. The bio-oil, bio-char and non-condensable gas were characterized using standard analytical techniques. The results revealed that the organic phase consists of hydrocarbons and various benzene derivatives, which can be further processed into fuels and valuable chemicals. The aqueous phase was predominantly water, acids, ketones, aldehydes and some phenolics and other water-soluble organics. The non-condensable gas was made up high hydrogen/carbon monoxide ratio suitable Page 2 of 37 for liquid fuel synthesis via Fischer-Tropsch Synthesis. The bio-char was a porous carbonaceous material with high energy content, which can be applied as a solid fuel, adsorbent or source of biofertilizer. This study demonstrated that Napier grass biomass is a viable feedstock for production of high-value bioenergy precursors.

The production and application of carbon nanomaterials from high alkali silicate herbaceous biomass

“…The emissions associated are accounted for and allocated in three fundamental categories; human health, energy resources and ecosystem quality 1 . This can be avoided by introducing oxygen-free/inert methods such as pyrolysis, which leads to a combination of multiple useful products in various phases that contribute positively to the circular economy via up-cycling and creation of added value products 2 . One of the well-known strategies of cleaner production practitioners is to increase production efficiency and reduce waste and emissions 3 .…”

State-of-the-Art Char Production with a Focus on Bark Feedstocks: Processes, Design, and Applications

“…Intermediate pyrolysis is carried out at lower heating rates and higher vapor residence times than fast pyrolysis, and approximately 30-40% char is obtained [47,48]. Intermediate pyrolysis chars were suggested for fuel or soil amendment applications based on the atomic C:O ratio, moisture content, and heating values [23,165,166]. Intermediate pyrolysis at a large scale is a relatively new method for the production of biochars, and information on their properties is scarce compared to studies on fast and slow pyrolysis [48].…”

In-situ Upgrading of Napier Grass Pyrolysis Vapour Over Microporous and Hierarchical Mesoporous Zeolites

“…Ratio energy output to energy input has been reported to be in the range of 25:1 with 25-35 oven dry tons/hectare biomass yield. This value corresponds to 100 barrels of oil energy equivalent per hectare [17][18][19]. Comparing with other energy grasses such as Miscanthus, switchgrass, these materials have only between 10 and 20 oven dry tons biomass yield per hectare per annum and require some nutrient input during cultivation [20][21][22][23][24][25].…”