Bioresource Technology Reports

(1)

Bioresource Technology Reports 14 (2021) 100677

Available online 4 March 2021

Low-oxygenated biofuels production from palm oil through hydrocracking process using the enhanced Spent RFCC catalysts

I. Istadi

^a^,^b^,^*

, Teguh Riyanto

^a^,^b

, Elok Khofiyanida

^a

, Luqman Buchori

^a

, Didi D. Anggoro

^a

, Indro Sumantri

^a

, Bagus H.S. Putro

^a

, Agyet S. Firnanda

^a

aDepartment of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro, Semarang, Central Java 50275, Indonesia

bLaboratory of Plasma-Catalysis (R3.5), Center of Research and Services - Diponegoro University (CORES-DU), Universitas Diponegoro, Semarang, Central Java 50275, Indonesia

A R T I C L E I N F O Keywords:

Hydrocracking RFCC catalysts Deoxygenation Palm oil Brønsted acid site Lewis acid site

A B S T R A C T

Utilization of the enhanced Spent Residue Fluid Catalytic Cracking (SRFCC) catalysts through the acid treatment was conducted for the palm oil hydrocracking process to produce biofuels. The catalysts were characterized using Pyridine-probed Fourier Transform Infrared (Pyridine-FTIR) spectroscopy and Brunauer−Emmett−Teller-Bar- rett−Joyner−Halenda (BET-BJH) method. The higher number of Brønsted acid sites on the enhanced SRFCC catalysts leads to the lower conversion of palm oil as well as lower deoxygenation activity because of the slower carbocations formation process as the initiation reaction. On the other hand, the Lewis acid sites on the enhanced SRFCC catalysts have a significant role in the deoxygenation reaction mechanism. Meanwhile, the catalysts surface area and pore size are responsible for tailoring the diffusion mechanism of the mass transfer process of reactant molecules. The introduction of hydrogen gas in the reaction system has a significant role in deoxygenation, double bond cleavage, and de-coking process mechanisms.

1. Introduction

The increase in energy demand and decrease in fossil fuel resources need to develop biofuels production process from renewable energy sources. Biofuels can be produced from biomass, fat, and vegetable oils (Albashabsheh and Heier Stamm, 2019; Istadi et al., 2021; Kazemi Shariat Panahi et al., 2019; Suchamalawong et al., 2019). However, fatty acids group vegetable oils are the most used feedstocks due to their availability to be processed through transesterification and cracking processes. The transesterification process produces a fatty acid alkyl ester (biodiesel) as the main product and glycerol as a by-product (Buchori et al., 2017). However, the cracking process is the preferred process due to its high performance in fatty acid conversion, either thermal or catalytic cracking. Many studies reported that the cracking process produces wide carbon ranges of hydrocarbons as biofuels, including gasoline, kerosene, and diesel ranges (Istadi et al., 2021).

Furthermore, the fractionated fuels product from the cracking process can be directly used as bio-gasoline, bio-kerosene, or biodiesel/green- diesel and do not need to be mixed with the fossil fuels (Sousa et al., 2018). Palm oil is the most favorable vegetable oil as a feedstock for

biofuels production due to the high content of long-chain hydrocarbon (Istadi et al., 2020a), the relatively equal ratio of saturated and unsat- urated oil content giving significant contribution to aromatic com- pounds in the liquid product (Beims et al., 2018; Pande et al., 2012), and abundantly available in the world especially Indonesia and Malaysia regions.

Some cracking processes of vegetable oils to biofuels (gasoline- kerosene-diesel hydrocarbons ranges) or fossil oils to lower hydrocarbons were developed include hydrocracking, or hydrocracking- deoxygenation (Al-Muttaqii et al., 2019; Mirzayanti et al., 2018; Trisu- naryanti et al., 2020), catalytic cracking (Istadi et al., 2020a; Siregar and Amin, 2006), or plasma-assisted cracking (Gharibi et al., 2015; Istadi et al., 2020b; Khani et al., 2015; Riyanto et al., 2020). The cracking or catalytic cracking reactions involved are quite complicated over mostly the solid acid catalysts and conducted at around 450 ^◦C (Riyanto et al., 2020). The main cracking product is gasoline-range and/or diesel-range hydrocarbons containing paraffins (alkane), olefins (alkene), and aromatic hydrocarbons. Other by-products are water and carbon dioxide.

Previous studies suggested that the catalysts with moderate acidity led to the formation of gasoline range liquid fuels type, and catalysts with

* Corresponding author at: Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro, Semarang, Central Java 50275, Indonesia.

E-mail address: [email protected] (I. Istadi).

Contents lists available at ScienceDirect

journal homepage: www.sciencedirect.com/journal/bioresource-technology-reports

https://doi.org/10.1016/j.biteb.2021.100677

Received 26 January 2021; Received in revised form 23 February 2021; Accepted 26 February 2021