Green chemicals from pulp production black liquor by partial wet oxidation

Abstract

To reduce greenhouse gas emissions, more sustainable sources of energy, fuel and chemicals are needed. Biomass side streams such as black liquor, which is a by-product of pulp production, has the potential to be used for this purpose. The aim of the study was the production of carboxylic acids, such as lactic acid, formic acid and acetic acid, from kraft and non-wood black liquor. The processes studied were partial wet oxidation (PWO) and catalytic partial wet oxidation (CPWO). The results show that the yield of carboxylic acid is higher when treated by PWO than the results from CPWO at temperatures of 170 °C and 230 °C. The results shows that the PWO process can increase the yield of carboxylic acids and hydroxy acids in black liquor, reduce lignin content and decrease pH, which makes further separation of the acids more favourable. The hydroxy acids are valuable raw materials for biopolymers, and acetic acid and formic acid are commonly used chemicals conventionally produced from fossil feedstock.

Bioenergy production and utilization in different sectors in Sweden: A state of the art review

“…Black liquor derived-lignin can be used in value-added applications such as in platform phenolic chemical products (Naron et al 2017). High levels of organic acids such as formic and lactic acids can be processed from black liquor by partial wet oxidation reaction with catalysts including iron activated carbon (Fe/AC), Fe/AC with hydrogen peroxide and iron (III) sulphate (Mishra et al 1995;Muddassar et al 2015).…”

A novel biorefinery integration concept for lignocellulosic biomass

“…The PWO studies examined for chemical production, e.g. the impacts of temperature and catalyst on the production of carboxylates from Kraft black liquor and wheat straw black liquor with the residence time of 30 minutes (Muddassar et al, 2015). PWO is also involved in an industrial application of lignin recovery from black liquor: namely LignoForce process, PWO of black liquor prior to acidification to enhance the filtration of lignin and to obtain sulphur-free lignin (Kouisni et al, 2016).…”

“…Therefore, the criteria of selecting the PWO conditions should involve the balance among: the minimum loss of TOC to maintain the organic content for liquid feedstock the maximum TOC for solid feedstock, i.e. maximum dissolution with minimum decomposition the maximum temperature to reduce the heating need in further steps the minimum residence time to reduce the investment cost the minimum oxygen pressure to reduce the operating cost The impacts of temperature, feedstock, catalyst and residence time were investigated for Kraft black liquor and wheat straw black liquor (Hassan, 2016;Muddassar et al, 2015). The optimum conditions were defined as 210 ºC and the oxygen partial pressure of 0.5 MPa with 10-20 minutes residence time.…”

Transitioning from a linear economy towards a circular economy: The case of the apparel industry

“…The hydrothermal processes involve the conversion by heat treatment and using water as the reaction media. The main examples are hydrothermal liquefaction (HTL) producing crude bio-oil (Toor et al, 2011), supercritical water gasification (SCWG) producing syngas (Yakaboylu et al, 2015), and partial wet oxidation (PWO) (Muddassar et al, 2015a(Muddassar et al, , 2015b. Figure 1 shows the simplified scheme of biomass processing.…”