Transition Metal Phosphides for the Catalytic Hydrodeoxygenation of Waste Oils into Green Diesel

Abstract

Recently, catalysts based on transition metal phosphides (TMPs) have attracted increasing interest for their use in hydrodeoxygenation (HDO) processes destined to synthesize biofuels (green or renewable diesel) from waste vegetable oils and fats (known as hydrotreated vegetable oils (HVO)), or from bio-oils. This fossil-free diesel product is produced completely from renewable raw materials with exceptional quality. These efficient HDO catalysts present electronic properties similar to noble metals, are cost-efficient, and are more stable and resistant to the presence of water than other classical catalytic formulations used for hydrotreatment reactions based on transition metal sulfides, but they do not require the continuous supply of a sulfide source. TMPs develop a bifunctional character (metallic and acidic) and present tunable catalytic properties related to the metal type, phosphorous-metal ratio, support nature, texture properties, and so on. Here, the recent progress in TMP-based catalysts for HDO of waste oils is reviewed. First, the use of TMPs in catalysis is addressed; then, the general aspects of green diesel (from bio-oils or from waste vegetable oils and fats) production by HDO of nonedible oil compounds are presented; and, finally, we attempt to describe the main advances in the development of catalysts based on TMPs for HDO, with an emphasis on the influence of the nature of active phases and effects of phosphorous, promoters, and preparation methods on reactivity.

Transition Metal Dichalcogenides for the Application of Pollution Reduction: A Review

“…Moreover, Co-and Nipromoted MoS 2 catalyst was also used to co-process diesel and vegetable oil via hydrodeoxygenation reaction [226]. Alvarez-Galvan et al [227] demonstrated that transition metals phosphides were useful as a hydrodeoxygenation catalyst for waste cooking oil to green biodiesel. More research work is required to explore the possibility of TMDC materials in this field.…”

Ni2P Nanoalloy as an Air‐Stable and Versatile Hydrogenation Catalyst in Water: P‐Alloying Strategy for Designing Smart Catalysts

“…In contrast, the use of metal–non‐metal nanoalloys, such as metal phosphide nanoalloy catalysts, has not been studied comprehensively. Few innovative metal phosphide catalysts have been reported in organic synthesis [19–24] despite their high catalytic potential as hydrotreating catalysts, as well as electrocatalysts and photocatalysts for energy conversion [25–31] . In this context, our research group has recently focused on exploring novel catalysis by metal phosphide nanoalloys.…”

Theoretical Investigation of the Deactivation of Ni Supported Catalysts for the Catalytic Deoxygenation of Palm Oil for Green Diesel Production

“…The mild acidity of the catalysts promotes the generation of many side reactions, as a result, coking of the catalyst may occur. Further reasons for the loss of catalytic activity may be sintering, poisoning or active metal leaching which reduces the number of active sites [17]. Kubička and Horáček [18] investigated the reasons for deactivation of hydrodesulphurization (HDS) catalysts during the deoxygenation of vegetable oils.…”