Biocatalytic desulfurization (BDS) of petrodiesel fuels

Abstract

Oil refineries are facing many challenges, including heavier crude oils, increased fuel quality standards, and a need to reduce air pollution emissions. Global society is stepping on the road to zero-sulfur fuel, with only differences in the starting point of sulfur level and rate reduction of sulfur content between different countries. Hydrodesulfurization (HDS) is the most common technology used by refineries to remove sulfur from intermediate streams. However, HDS has several disadvantages, in that it is energy intensive, costly to install and to operate, and does not work well on refractory organosulfur compounds. Recent research has therefore focused on improving HDS catalysts and processes and also on the development of alternative technologies. Among the new technologies one possible approach is biocatalytic desulfurization (BDS). The advantage of BDS is that it can be operated in conditions that require less energy and hydrogen. BDS operates at ambient temperature and pressure with high selectivity, resulting in decreased energy costs, low emission, and no generation of undesirable side products. Over the last two decades several research groups have attempted to isolate bacteria capable of efficient desulfurization of oil fractions. This review examines the developments in our knowledge of the application of bacteria in BDS processes, assesses the technical viability of this technology and examines its future challenges. IntroductionBiotechnology is now accepted as an attractive means of improving the efficiency of many industrial processes, and resolving serious environmental problems. One of the reasons for this is the extraordinary metabolic capability that exists within the bacterial world. Microbial enzymes are capable of biotransforming a wide range of compounds, and the worldwide increase in attention being paid to this concept can be attributed to several factors, including the presence of a wide variety of catabolic enzymes and the ability of many microbial enzymes to transform a broad range of unnatural compounds (xenobiotics) as well as natural compounds. Biotransformation processes have several advantages compared with chemical processes, including: (i) microbial enzyme reactions are often more selective; (ii) biotransformation processes are often more energy-efficient; (iii) microbial enzymes are active under mild conditions; and (iv) microbial enzymes are environment-friendly biocatalysts. Although many biotransformation processes have been described, only a few of these have been used as part of an industrial process. Many opportunities remain in this area.Petroleum biotechnology is based on biotransformation processes. Petroleum microbiology research is advancing on many fronts, spurred on most recently by new knowledge of cellular structure and function gained through molecular and protein engineering techniques, combined with more conventional microbial methods. Current applied research on petroleum microbiology encompasses oil spill remediation, fermenter-and wetland-based hydrocarbon...

Biodesulfurization of Dibenzothiophene by Two Bacterial Strains in Cooperation with Fe3O4, ZnO and CuO Nanoparticles

“…In this process microorganisms remove sulfur selectively without breaking the heterocycles. The fuel value is not reduced in this four-step (4S) pathway [5,6]. By using DBT as a substrate in 4S pathway, three intermediate and a final compounds are produced which 2-hydroxybiphenyl (2-HBP) is the last one [7].…”

“…Although this process is plenty useful for removing the element from aliphatic and some aromatic compounds, it does not have enough influence on some cyclic molecules such as dibenzothiophene and its alkylated derivatives. On the other hand, HDS requires high temperature and high pressure which cost a huge budget [3][4][5]. Biodesulfurization has been the promising technology to compensate the weak points of HDS.…”

Biodesulfurization of Sour Crude Oil

“…In general, organic sulfur compounds exist in crude oil in two forms namely, heterocyclics and non-heterocyclics. However, there seems to be more research attention on heterocyclic sulfur compounds compared to non-heterocyclic sulfur compounds (Mohebali & Ball, 2008). Figure 1 shows organic sulfur compounds can be classified as acidic sulfur compounds (which include mercaptanorthiols) and non-acidic as sulfides (such as disulfides and thiophene) (Duissenov, 2012;.…”

“…Hydrodesulfurization (HDS) is the most commonly used method in refineries for transforming sulfur into H 2 S. Conventional HDS process requires intensive energy usage, costly, and ineffective as the ratio and forms of organosulfur compounds increase (Mohebali & Ball, 2008). This technology is widely used in the oil industry and requires extreme industrial conditions such as 200-340ºC temperature and 5 MPa pressure (Egorova, 2003) Here, because the desulfurization level is dependent on the type of petroleum, the sour heavy oil requires deep hydrogenation at very high pressure and temperature of 200-425ºC and 1 to 18 MPa (Javadli, 2011).…”

Desulphurization of Liquid Fuels by Selective Adsorption Through Mineral Clays as Adsorbents

“…Recently the researchers have developed several new processes for desulphurization which include biodesulphurization [5,6], desulphurization by precipitation [7,8], oxidative desulphurization [9][10][11] and adsorptive desulphurization [12]. Out of these the adsorptive desulphurization is gaining more popularity due to producing promising results while operating at ambient pressure and temperature.…”