Success story

Short overview of the project.

Natural clay supported metal nanocatalysts were prepared and explored in catalytic hydrogenation of squalene into squalane (widely used in cosmetic, nutraceutical and pharmaceutical formulators), where clay/Pd catalyst were most effective at 200-300 °C and 4-10 bar H2 pressure under solvent free conditions. The catalysts are highly recyclable without any significant drop in activity. In extension to this work, non-noble metal (Ni and Co)-based clay catalysts were prepared and utilized in selective deoxygenation of algae oil and non-edible oil (such as jatropha oil) to produce diesel-grade hydrocarbons at <300 °C and <40 bar H2 pressure. Ni/clay catalyst promotes decarboxylation/decarbonylation, whereas remarkable selectivity in hydrodeoxygenation (HDO) is achieved with Co/clay catalysts. The HDO process provides higher carbon atom economy and energy value over decarboxylation/decarbonylation, while further reducing the formation of greenhouse gases such as CO2 and CH4. The catalysts are stable and recyclable under given reaction conditions. Metal leaching is less than 1 ppm during hydrotreatment. This process is advantageous in terms of metal-to-substrate ratio, use of solvents and their concentration, and comparable HDO selectivity over the previously reported catalysts. A hydroprocessing reaction was also performed under solvent free conditions, which could be useful in industrial applications of this approach.

Tackling an important problem:

1. The industrial methods reported for catalytic hydrogenation of squalene into squalane require extensive purification of product mixture to remove other impurities including leached metal species.

2. Fuel from biomass feedstock is a viable solution. The materials with high oxygen content such as lignin and carbohydrate based substrates are less attractive for such transformations. However, triglycerides and fatty acid/esters are suitable precursors, and the use of edible/non-edible oils is considered more appropriate. Therefore, several processes such as pyrolysis and trans-esterification have been developed. However, the presence of oxygen content in these processed products delimits their use in diesel engines due to their different physical and chemical properties. To overcome these limitations, the hydrotreatment process is investigated for converting triglycerides and free fatty acids derived from oils into straight chain diesel-grade hydrocarbons (second generation biodiesel). In this perspective, microalgae have the potential to act as a renewable energy resource due to a non-competitive high growth rate with respect to the plants. The presence of high mono-, di-, and triglyceride in algae oil is responsible for relatively low oxygen content. Deoxygenation of long chain fatty acids (C12−C22) produces straight chain hydrocarbons with high cetane number, and thus useful for diesel engines.

Impactful breakthrough:

1. Present innovation involves the use of natural clay as a catalysis. Though relatively expensive Pd metal is incorporated in the catalytic system, the recyclability and stability of catalyst in synthesizing squalane are very crucial. The ease in hydroprocessing and purification of product is profitable.

2. Sulfided metal catalysts are generally used for deoxygenation of non-edible oil, microalgae oil and model compounds. However, the oxygenates and moisture cause deactivation of sulfided catalysts and require addition of a sulfur agent during the reaction. This process is unwelcome for both practical and environmental reasons. To overcome this, a green natural clay-based catalytic system is developed for efficient and selective conversion of algae oil, non-edible oil into diesel grade hydrocarbons. The complete hydrogenation and deoxygenation could be realized solvent free conditions. The use of non-noble metals such as Ni and Co is an important feature. The selectivity toward hydrodeoxygenation further increased with low metal loadings. Such deoxygenation selectivity has not been observed previously for Ni and Co catalysts. The catalysts prepared from natural clay are considered green due to good recyclability and low metal leaching (less than 1 ppm) during the hydroprocessing reaction

Innovative breakthrough:

1. The process of synthesizing squalane has advantages of having very low metal leaching and highly selective full hydrogenation of squalene (therefore, no further purification required). We believe that this process will be energy efficient and cost effective if successfully scaled up for the industrial production. This is most successful catalyst ever reported for hydrogenation of Squalene. The reaction has been tested at up to 100 gm scale.

2. The solvent free approach is useful in reducing the cost, and easy processing of algae oil and related compounds. The utilization of non-noble metals and naturally abundant clay under solvent free conditions herein provides further opportunities in the large scale production of diesel grade hydrocarbons from algae oil. The process is highly successful up to kilogram level.

What are the next steps or additional support needed to maximise the impact of this breakthrough?

Although the deoxygenation of glycerides cannot be performed in the absence of hydrogen gas (must required for the hydrogenolysis of ester bond as well as to avoid catalyst deactivation by carbon formation), the use of hydrogen gas can be minimized to a defined molar concentration with respect to the substrate by mixing with nitrogen gas. The success of this strategy will reduce the processing cost further. The use of these cost-effective and efficient catalysts will be explored in the production of fuel-grade hydrocarbons from diverse substrates; such as algae oil, non-edible oil, vegetable oil and animal fat. Large scale production of fuel grade hydrocarbons from biomass derived substrates in fixed bed and fluidized bed reactors will be endeavored. Testing of thus produced biofuel will be carried out, and the requirement of any modifications and/or additives will be fulfilled to match up with the performance of fossil fuel. Focus will be shifted to achieve more cracking during the treatment of non-edible oil and algae oil for the production of jet fuel grade hydrocarbons. Similarly, other catalysts will be designed to promote selective isomerization of hydrocracked substances to obtain high octane rating renewable gasoline fuel.