Production of Bio-Hydrogenated Diesel by Hydrotreatment of High-Acid-Value Waste Cooking Oil over Ruthenium Catalyst Supported on Al-Polyoxocation-Pillared Montmorillonite

Yanyong Liu,Kazuhisa Murata,Rogelio Sotelo-Boyás,Tomoaki Minowa,Kinya Sakanishi

doi:10.3390/catal2010171

Yanyong Liu, Kazuhisa Murata + Show 3 more

Open Access

https://doi.org/10.3390/catal2010171

Copy DOI

Abstract

Waste cooking oil with a high-acid-value (28.7 mg-KOH/g-oil) was converted to bio-hydrogenated diesel by a hydrotreatment process over supported Ru catalysts. The standard reaction temperature, H2 pressure, liquid hourly space velocity (LHSV), and H2/oil ratio were 350 °C, 2 MPa, 15.2 h–1, and 400 mL/mL, respectively. Both the free fatty acids and the triglycerides in the waste cooking oil were deoxygenated at the same time to form hydrocarbons in the hydrotreatment process. The predominant liquid hydrocarbon products (98.9 wt%) were n-C18H38, n-C17H36, n-C16H34, and n-C15H32 when a Ru/SiO2 catalyst was used. These long chain normal hydrocarbons had high melting points and gave the liquid hydrocarbon product over Ru/SiO2 a high pour point of 20 °C. Ru/H-Y was not suitable for producing diesel from waste cooking oil because it formed a large amount of C5–C10 gasoline-ranged paraffins on the strong acid sites of HY. When Al-polyoxocation-pillared montmorillonite (Al13-Mont) was used as a support for the Ru catalyst, the pour point of the liquid hydrocarbon product decreased to −15 °C with the conversion of a significant amount of C15–C18 n-paraffins to iso-paraffins and light paraffins on the weak acid sites of Al13-Mont. The liquid product over Ru/Al13-Mont can be expected to give a green diesel for current diesel engines because its chemical composition and physical properties are similar to those of commercial petro-diesel. A relatively large amount of H2 was consumed in the hydrogenation of unsaturated C=C bonds and the deoxygenation of C=O bonds in the hydrotreatment process. A sulfided Ni-Mo/Al13-Mont catalyst also produced bio-hydrogenated diesel by the hydrotreatment process but it showed slow deactivation during the reaction due to loss of sulfur. In contrast, Ru/Al13-Mont did not show catalyst deactivation in the hydrotreatment of waste cooking oil after 72 h on-stream because the waste cooking oil was not found to contain sulfur-containing compounds.

Highlights

The increase of environmental concerns and the depletion of petroleum reserves have stimulated the search for alternative renewable fuels to avoid climate change and energy shortage [1]
The value of the basal plane reflection (d001) at the lowest angle in the X-ray diffraction (XRD) pattern includes the thickness of a host layer and the gallery height of an interlayer region [26,33]
The waste cooking oil containing 16.9 wt% free fatty acids was converted to mixed paraffins over

Summary

Introduction

The increase of environmental concerns and the depletion of petroleum reserves have stimulated the search for alternative renewable fuels to avoid climate change and energy shortage [1]. Bio-diesel, which has been recognized as “green fuel”, is an important alternative fuel made from renewable resources such as vegetable oil [2]. Bio-diesel is a renewable fuel with environmental benefits, the utilization of nonfood biomass is important from the viewpoint of food supply [3]. Waste cooking oil is an important biomass resource without competition from food uses [4]. The production of bio-diesel from waste cooking oil has been studied worldwide [6,7,8,9]

Objectives

Results

Conclusion