Catalytic Materials for Demetallation of Algal Biocrude

As our planet’s energy resources grow scarce, we must become cultivators of energy. Algae is a renewable resource that has fast growth rate and characteristics that point to it being favorable for the production of liquid fuel. However, algae, and its produced crude bio-oil, stores high concentrations of metals, especially iron, in its composition, which produces problems in petroleum refineries, as they are not designed to process iron infused feedstocks. Therefore, different types of catalysts, such as CoMo/silica-alumina, activated carbon, Ru/C and Ni/silica-alumina, were used under different experimental conditions to obtain the one with best demetallation properties and biocrude yield. To obtain our biocrude, batch-mini reactors are loaded with water, algae, catalyst, and enter a pre-heated sand-bath for hydrothermal liquefaction (HTL). After cooling down, the reactors’ contents are extracted with a solvent and then centrifuged to obtain different phases of products: organic, solid and aqueous. The organic phase, where the biocrude exists, is extracted and dried. Once the biocrude yield is known, the biocrude is dissolved with another solvent and run through the inductively coupled plasma optical emission spectrometry machine to know the metal composition contained in the biocrude. The solid and aqueous phases are also analyzed, using multiple characterization techniques, in order to obtain a profile of where all the metals are being deposited after HTL. It was found that the best experimental conditions in order to obtain the best demetallation and biocrude yield were using: methyl tert-butyl ether as a solvent, temperature of 400˚C, an hour of HTL, and more amount of catalyst. It was also found that, so far, the best catalyst for algal biocrude demetallation is Ni/silica-alumina, and that most metals after HTL are deposited in the solid phase. However, many more catalysts and characterization techniques must be employed in the future in order to gain more information and finite results for this area of research.