A pinboard by
Kalidas Mainali

Graduate student/RA, Washigton State University


Chromatographic techniques are widely used to detect oxygenated compounds in jet fuel.

Jet fuel is a complex mixture of hundreds of species including normal alkanes, cycloalkanes, branched alkanes and aromatics. Except these, other non- hydrocarbon compounds such as oxygen, sulfur, and nitrogen hetero-atomic species are also present in trace quantities. The important classes of these trace compounds include phenols, indoles, thiophenes, amines and others. The concentration of polar species in jet fuel such as phenols are detrimental to engines and the concentration of these oxygenated compounds are responsible for thermal instability of engine and potential hazards to aircraft. Therefore, detection of these trace amounts of oxygenated compounds are vital in fuel industry. So, development of new analytical technique (biosensor) to detect oxygenated molecules in jet-A will be beneficial in fuel-industry.


Nanoporous materials forge a path forward to enable sustainable growth: Technology advancements in fluid catalytic cracking

Abstract: An overview is presented on the central role that zeolites and other nanoporous materials currently play in the Fluid Catalytic Cracking (FCC) process as well as how this role evolved over the course of the years since its inception. Today, utilization in FCC constitutes the vast majority of global zeolite catalyst consumption by volume. FCC is the main conversion process in a typical fuels refinery, and as the most critical ingredient of the catalyst, zeolites are responsible for producing majority of the gasoline used around the world as well as taking an important role in the production of other transportation fuels (e.g., diesel, jet fuel) and building blocks for the petrochemical industry (e.g., propylene, butylenes). Therefore, it can be stated that zeolite catalysts fuel our industrialized society and provide the building blocks for its advancement; consequently, zeolites have a direct impact on the future of the global economy and its sustainability. Strategies that involve zeolites and other nanoporous materials for improving performance of FCC operation and ensuring its environmental sustainability were reviewed. Zeolite modifications were examined with each leading to an improvement in zeolite stability under severe conditions in an FCC unit. The importance of diffusion pathways within an FCC catalyst particle, leading to higher accessibility of the active zeolite sites, were explored, and the importance of a well-designed catalyst architecture, allowing FCC feed, intermediates, and final products to diffuse freely in and out of the catalyst particle were discussed. The role of contaminant metals in FCC was investigated, and some mitigation strategies for the most common FCC contaminants, nickel and vanadium, were presented. The impact of contaminant iron was discussed alongside catalyst architecture, particularly surface porosity of the catalyst particle. Utilization of other nanoporous materials in FCC, especially as environmental additives, was summarized. Testing considerations were screened with an emphasis on matching laboratory deactivation to refinery FCC observations.

Pub.: 02 Apr '17, Pinned: 19 Jun '17

Life Cycle Water Footprint Analysis for Rapeseed Derived Jet Fuel in North Dakota

Abstract: Water footprint analysis, when combined with water-focused life cycle assessment, can be an effective systems analysis tool for biofuel sustainability.Rapeseed is considered to be a promising sources for hydroprocessed ester and fatty acid (HEFA) jet fuel production as a means to address energy security and climate change mitigation. However, concerns have been raised about its impact on water, as large-scale biofuel production may place pressure on fresh water supplies and water quality. Water footprint (WF) analysis, when combined with water-focused life cycle assessment (LCA), can be an effective system analysis tool for water sustainability. This study developed a life cycle water footprint analysis informed by inputs from multiple models for rapeseed HEFA jet fuel production in North Dakota and evaluated the environmental impacts on water utilization and water quality due to large scale HEFA jet production. The biogeochemical-based EPIC model was incorporated to simulate crop growth that influences the hydrological cycle. Systematic LCA models were built in SimaPro to conduct life cycle blue WF analysis. Results using energy allocation indicate that rapeseed derived HEFA jet fuel has a WF of 131–143 m3 per GJ fuel over a rapeseed price range of $470–600, including all green, blue, and gray WF components. Discussions also indicate the importance of incorporating allocation within a life cycle approach when conducting biofuel WF analysis.

Pub.: 06 Apr '17, Pinned: 19 Jun '17

Direct production of light olefins from syngas over potassium modified Fe–Mn catalyst

Abstract: A series of potassium promoted Fe–Mn catalysts for light olefin synthesis from CO hydrogenation were prepared by the co-precipitation-calcination-impregnation method. The impact of potassium promoter on the textural properties, reduction behavior, adsorption of hydrogen, bulk phase composition and their correlation with Fischer–Tropsch synthesis (FTS) performances were emphatically studied. As revealed by N2 physisorption, the increasing of potassium had no distinct effect on the size of α-Fe2O3 and surface area. H2 temperature-programmed reduction/desorption showed that potassium inhibited the reduction and hydrogen adsorbability of catalysts. CO temperature-programmed desorption showed that potassium enhanced the CO adsorption of catalysts. X-ray photoelectron spectroscopy indicated the enrichment of promoter atoms on the surface of catalysts. The X-ray diffraction and Mössbauer effect spectroscopy results revealed that potassium made carburization easy. After reduction with syngas (H2/CO = 20) for 48 h, FTS test was performed with the syngas (H2/CO = 3.5) in the high temperature Fischer–Tropsch synthesis process. The maximum of CO conversion and selectivity to light olefins was noted on increasing K content (2.8 mol% K/Fe), followed by a significant decline at the excessive potassium level. At the point, the selectivity of light olefins and olefin/paraffin (C2–C4) was 27.75 mol% and 8.54. The results indicated that potassium promoter could inhibit the water gas shift reaction, suppress hydrogenation ability, which promoted the production of light olefins via suppressing the secondary hydrogenation reaction.

Pub.: 25 May '14, Pinned: 19 Jun '17

Synergetic integration of laccase and versatile peroxidase with magnetic silica microspheres towards remediation of biorefinery wastewater.

Abstract: In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst. ᅟ Graphical abstract.

Pub.: 19 Jun '17, Pinned: 19 Jun '17