• Energy Research

There is an increasing trend to use bio-polyethene and bio-polypropene in Europe. However there is at present very limited production capacity available for producing the base chemicals that are used in polymerization processes. Therefore a production route for green ethene, propene and 1,3-butadiene is evaluated on a pilot plant scale starting from triglyceride and fatty acid based biomass. The first step consists of removing suspended solids, solubilized metals and phosphorus from the feedstock. The next step is catalytic hydrodeoxygenation (HDO) of the purified product to reduce oxygen to less than 0.1 wt%. Finally the HDO product is cracked into light olefins in a steam cracking pilot plant. For a coil outlet temperature of 835 °C and a steam dilution of 0.45 kg kg−1 the product yields amount to 38 wt% ethene, 20 wt% propene and 7.5 wt% 1,3-butadiene. This is significantly higher than the yields that are obtained when cracking classical fossil based naphtha under similar process conditions. Moreover, the fouling tendency of the renewable feed is also a factor of 2 smaller than that for naphtha. The pilot plant data have been used to scale up to a commercial scale steam crackers by applying a validated fundamental kinetic model, indicating the high potential of this route for producing green high value chemicals with a 20% reduction in CO2 emissions as compared to a naphtha cracker.

Bio-oils produced by fast pyrolysis of lignocellulosic biomass have proven to be a promising, clean, and renewable energy source. To better assess the potential of using bio-oils for the production of chemicals and fuels a new comprehensive characterization method is developed. The combination of the analyical power of GC×GC-FID and GC×GC-TOF-MS allows to obtain an unseen level of detail for both crude and hydrotreated bio-oils originated from pine wood biomass. The use of GC×GC proves to be essential to capture the compositional differences between crude and stabilized bio-oils. Our method uses a flame ionization detector to quantify the composition, while GC×GC-TOF-MS is used for the qualitative analysis. This method allows quantification of around 150 tentatively identified compounds, describing approximately 80% of total peak volume. The number of quantified compounds in bio-oils is increased with a factor five compared to the present state-of-the-arte. The necessity of using multiple internal standards (dibutyl ether and fluoranthene) and a cold-on column injector is also verified.

Tall oil fractions obtained from Norwegian spruce pulping were hydrodeoxygenated (HDO) at pilot scale using a commercial NiMo hydrotreating catalyst. Comprehensive two dimensional gas chromatography (GC×GC) showed that HDO of both tall oil fatty acids (TOFA) and distilled tall oil (DTO) produced highly paraffinic hydrocarbon liquids. The hydrotreated fractions also contained fatty acid methyl esters and norabietane and norabietatriene isomers. Steam cracking of HDO-TOFA in a pilot plant revealed that high light olefin yields can be obtained, with 35.4 wt.% of ethene and 18.2 wt.% of propene at a coil outlet pressure (COP) of 1.7 bara, a dilution of 0.45 kg(steam)/kg(HDO-TOFA) and a coil outlet temperature (COT) of 820 °C. A pilot plant coking experiment indicated that cracking of HDO-TOFA at a COT of 850 °C results in limited fouling in the reactor. Co-cracking of HDO tall oil fractions with a typical fossil-based naphtha showed improved selectivity to desired light olefins, further demonstrating the potential of large scale olefin production from hydrotreated tall oil fractions in conventional crackers.