Adriaan R. P. van Heiningen
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Professor Emeritus
Phone: 207.581.2278 |
Research Interests
Fundamental chemical engineering aspects of pulp production and forest biomass conversion processes; in particular those of pulping, bleaching, recovery of pulping chemicals, and production of bio-based chemicals, biomaterials such as nanocellulose, and biofuels.
My work is interdisciplinary, and strives to integrate a chemical mechanistic approach with that of transport phenomena, mass balances and an overall process concept.
Current Research
Integrated Forest Products Refinery (IFPR)
My IFPR work focuses on the production of bio-based chemicals, biomaterials and biofuels from hemicelluloses and lignin extracted from wood chips as side-steams as part of pulp or nanocellulose production. The rational for the IFPR is twofold. First, the US pulp and paper industry needs new income to remain viable with the emergence of very large and technologically advanced mills in tropical countries which also have advantages in terms of wood and labor cost. Since US mills already have environmental permits and the infrastructure to handle forest biomass material, the integrated production of high value-added biofuels and new biomaterials from waste streams would lead to competitive synergies, new markets and increased product flexibility. Secondly, fossil-fuel CO2 emissions and foreign fossil fuel dependence must be reduced. Managed forests have enormous untapped potential as a carbon neutral resource for renewable and biodegradable materials and chemicals.
Selectivity Improvement during Oxygen Bleaching
Oxygen delignification is essential for pulp mills to meet stringent environmental regulations. Unfortunately, the degree of delignification in a single oxygen stage is limited to about 50%, since further lignin removal leads to unacceptable cellulose degradation and excessive yield loss. Therefore my research focusses on extended delignification far beyond 50% while maintaining cellulose degradation and yield loss at acceptable level by changing the reactor system, operating conditions and use of additives which are practical and economical at industrial scale.
Utilization of Black Liquor and Lignin for Chemicals and Fuels
Modern Kraft pulp mills produce excess energy. In addition the combustion of black liquor in recovery boilers is the bottle neck in many mills for increased pulp production. Thus the direct use of excess black liquor or its lignin obtained by acid precipitation is of interest to increase pulp production as well as to obtain new revenue in the form of commodity chemicals and biofuels. Therefore we are investigating different hydrothermal and pyrolysis techniques with or without additives to convert the organics/lignin in black liquor to value-added products.
Use of Waste Lignocellulosics for Biofuels Production
Pretreatment is used to open-up the structure of lignocellulosic biomass to allow near-complete enzymatic hydrolysis of the cellulose at commercially economic enzyme charges, and is normally followed by fermentation to ethanol or butanol. My group is focusing on different “pretreatment” techniques such as formic acid reinforced prehydrolysis, low temperature alkaline treatment and AVAP® fractionation (SO2-Ethanol-Water). These technologies have in common that they avoid formation of “sticky” lignin precipitates and significant degradation of the dissolved hemicelluloses. Feedstocks which we presently use are low cost wheat straw, sugarcane straw and forest biomass. An important consideration in our research is process intensification and integration so as to minimize the number of process steps and thus capital cost.
Selected Publications