Catalytic Hydroprocessing Research Articles

Life cycle greenhouse gas emissions analysis of catalysts for hydrotreating of fast pyrolysis bio-oil

Bio-oil from fast pyrolysis of biomass requires multi-stage catalytic hydroprocessing to produce hydrocarbon drop-in fuels. One process design currently in development involves fixed beds of ruthenium-based catalyst and conventional petroleum hydrotreating catalyst. As the catalyst is spent over time as a result of coking and other deactivation mechanisms, it must be changed out and replaced with fresh catalyst. A main focus of bio-oil upgrading research is increasing catalyst lifetimes to 1 year. Biofuel life cycle greenhouse gas (GHG) assessments typically ignore the impact of catalyst consumed during fuel conversion as a result of limited lifetime, representing a data gap in the analyses. To help fill this data gap, life cycle GHGs were estimated for two representative examples of fast pyrolysis bio-oil hydrotreating catalyst, NiMo/Al2O3 and Ru/C, and integrated into the conversion-stage GHG analysis. Life cycle GHGs are estimated at 5.5 kg CO2-e/kg catalyst for NiMo/Al2O3. Results vary significantly for Ru/C, depending on whether economic or mass allocation methods are used. Life cycle GHGs for Ru/C are estimated at 80.4 kg CO2-e/kg catalyst using economic allocation and 13.7 kg CO2-e/kg catalyst using mass allocation. Contribution of catalyst consumption to total conversion-stage GHGs at 1-year catalyst lifetimes is 0.5% for NiMo/Al2O3 and 5% for Ru/C when economic allocation is used (1% for mass allocation). This analysis does not consider the use of recovered metals from catalysts and other wastes for catalyst manufacture and therefore these are likely to be conservative estimates compared to applications where a spent catalyst recycler can be used.

Commercial analysis of catalytic hydroprocessing technologies in producing diesel and gasoline by light cycle oil

Four main catalytic hydro-processing technologies of light cycle oil (LCO) were investigated in detail under typical pilot-scale operations aiming to provide industrial analysis of oil quality upgrading and to meet the various end-use applications. It is found that ultra-deep hydrodesulfurization (HDS) technology can effectively remove sulfur and nitrogen, however its performance on the improvement of cetane number and decreasing of density is limited. The property makes it suitable for production of fuel oils. Maximally improving LCO cetane number (MCI) technology is favorable for producing diesel with high cetane number by partial ring-opening of aromatics without side-chain cleavage. Medium-Pressure Hydro-upgrading (MHUG) technology partially converts LCO into naphtha for production of diesel with low density and high cetane number at medium pressure. Meanwhile, the by-product-heavy naphtha with high potential aromatic content occurs. Moreover, LCO hydrocracking (FD2G) technology employs relatively higher temperature with varied pressure, avoiding thermodynamic limits, to promote the conversion of di- and tri-aromatics into monoaromatics. This technology not only produces high octane number gasoline, but also upgrades the quality of diesel. The industrial analysis here could guide the design and optimization of LCO hydro-processing technology for fuel quality upgrading.

Integration of catalytic fast pyrolysis and hydroprocessing: a pathway to refinery intermediates and “drop-in” fuels from biomass

Biocrude obtained from catalytic fast pyrolysis could be hydrotreated in a single-stage without preprocessing and stabilization steps.

Catalytic hydroprocessing of microalgae-derived biofuels: a review

This article reviews the state-of-the-art in the hydroprocessing of microalgae-based biofuels, catalyst development, and the effect of process parameters on hydrotreated algal fuels.

Liquid Fuels From Ethylene Tar by Two-stage Catalytic Hydroprocessing

Two-stage hydroprocessing of ethylene tar was performed on bench-scale equipment under typical reaction conditions of hydrogen pressure of 6 MPa, liquid hourly space velocity of 0.8 h–1, H2/oil volume ratio of 1,600, first-stage temperature of 360°C, and second-stage temperature of 380°C. Alumina-supported molybdenum-nickel (Mo-Ni) and tungsten-nickel (W-Ni) catalysts, which were prepared through combinational technologies of ultrasonic-assisted impregnation and temperature-programming, were filled in the first and second stages, respectively. Gasoline (≤180°C) and diesel (180–360°C) fractions separated from the produced oil were analyzed. Results showed that the ethylene tar can be considerably upgraded through two-stage catalytic hydroprocessing, and fuels with sulfur and nitrogen contents of less than 10 and 2 ppm, respectively, were obtained.

Catalytic hydroprocessing of fatty acid methyl esters to renewable alkane fuels over Ni/HZSM-5 catalyst

A series of Ni/HZSM-5 catalysts with different Ni loading and Si/Al ratios were prepared by incipient wetness impregnation. The physicochemical properties of the catalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2-adsorption, temperature-programmed desorption of ammonia (NH3-TPD), and thermogravimetric (TG) analysis. Moreover, their catalytic performance was investigated for the hydroprocessing of long-chain unsaturated fatty acid methyl esters (FAMEs) to renewable alkane fuels using a high-pressure fixed bed reactor system with a facility for online analysis. The different Ni loading and Si/Al ratios of the catalysts, as well as the influence of reaction conditions such as temperature, pressure, H2/oil molar ratio, and liquid hourly space velocity (LHSV), were studied in detail. The NiO aggregates dispersed on the surface of the support clearly increased the acidity after H2 reduction, thus significantly affecting the catalytic performance. Temperature and pressure played crucial roles in the conversion of FAMEs and selectivity for gasoline or jet or diesel alkane. Hydroprocessing over 10wt% Ni/HZSM-5 (Si/Al=25) at 280°C, a H2 pressure of 0.8MPa, an LHSV of 4h−1, and with a highly purified H2/oil molar ratio of 15 led to a high selectivity of 88.2% for C5–C18 liquid alkanes, which includes 8% of gasoline alkane, 32.5% of jet alkane and 47.7% of diesel alkane, along with appropriate isomerization selectivity of 27.0%, while the conversion of FAME reached 85.1%. To demonstrate the potential of this catalyst for practical applications, its stability in the hydroprocessing of FAMEs was also investigated. The conversion of FAMEs decreased to 30.1% over 10wt% Ni/HZSM-5 (Si/Al=25) after operation for 80h. Catalyst deactivation was predominantly caused by the deposition of carbon which causes blockage of the pores for FAMEs as evidence from TG analysis.

Hydrocarbon Liquid Production via Catalytic Hydroprocessing of Phenolic Oils Fractionated from Fast Pyrolysis of Red Oak and Corn Stover

Phenolic oils were produced from fast pyrolysis of two different biomass feedstocks, red oak and corn stover, and evaluated in hydroprocessing tests for production of liquid hydrocarbon products. The phenolic oils were produced with a bio-oil fractionating process in combination with a simple water wash of the heavy ends from the fractionating process. Phenolic oils derived from the pyrolysis of red oak and corn stover were recovered with yields (wet biomass basis) of 28.7 and 14.9 wt %, respectively, and 54.3% and 60.0% on a carbon basis. Both precious metal catalysts and sulfided base metal catalyst were evaluated for hydrotreating the phenolic oils, as an extrapolation from whole bio-oil hydrotreatment. They were effective in removing heteroatoms with carbon yields as high as 81% (unadjusted for the 90% carbon balance). There was substantial heteroatom removal with residual O of only 0.4% to 5%, while N and S were reduced to less than 0.05%. Use of the precious metal catalysts resulted in more saturate...

Selective nickel-catalyzed conversion of model and lignin-derived phenolic compounds to cyclohexanone-based polymer building blocks.

Valorization of lignin is essential for the economics of future lignocellulosic biorefineries. Lignin is converted into novel polymer building blocks through four steps: catalytic hydroprocessing of softwood to form 4-alkylguaiacols, their conversion into 4-alkylcyclohexanols, followed by dehydrogenation to form cyclohexanones, and Baeyer-Villiger oxidation to give caprolactones. The formation of alkylated cyclohexanols is one of the most difficult steps in the series. A liquid-phase process in the presence of nickel on CeO2 or ZrO2 catalysts is demonstrated herein to give the highest cyclohexanol yields. The catalytic reaction with 4-alkylguaiacols follows two parallel pathways with comparable rates: 1) ring hydrogenation with the formation of the corresponding alkylated 2-methoxycyclohexanol, and 2) demethoxylation to form 4-alkylphenol. Although subsequent phenol to cyclohexanol conversion is fast, the rate is limited for the removal of the methoxy group from 2-methoxycyclohexanol. Overall, this last reaction is the rate-limiting step and requires a sufficient temperature (>250 °C) to overcome the energy barrier. Substrate reactivity (with respect to the type of alkyl chain) and details of the catalyst properties (nickel loading and nickel particle size) on the reaction rates are reported in detail for the Ni/CeO2 catalyst. The best Ni/CeO2 catalyst reaches 4-alkylcyclohexanol yields over 80 %, is even able to convert real softwood-derived guaiacol mixtures and can be reused in subsequent experiments. A proof of principle of the projected cascade conversion of lignocellulose feedstock entirely into caprolactone is demonstrated by using Cu/ZrO2 for the dehydrogenation step to produce the resultant cyclohexanones (≈80 %) and tin-containing beta zeolite to form 4-alkyl-ε-caprolactones in high yields, according to a Baeyer-Villiger-type oxidation with H2 O2 .

Water-washing to reduce metals in oils extracted from Nannochloropsis algae for potential FCC feedstock

Abstract Algae cultivation offers the potential to produce biofuels with much higher productivity than conventional soil-based crops. Organic oils can be extracted from algae using solvents such as alcohols and paraffins. A challenge is to define the most economical means to process these extracted oils into products such as chemical intermediates and liquid fuels. One approach is to add algal oils directly into the petroleum-based feeds to existing refinery processes such as fluid catalytic cracking (FCC) or hydroprocessing. Maximum acceptable levels were defined for contaminants such as sodium, potassium, calcium, phosphorus, and nitrogen in the feed to an FCC unit, based on refinery experience. Cracking runs in a laboratory unit confirmed the large decrease in conversion for high levels of sodium and potassium. For a laboratory sample of Nannochloropsis algae, the level of metals was far too high in the whole algae or in oils extracted from the algae using ethanol or n-heptane to allow their inclusion in FCC feedstock, even at a level of 2% algal product in the FCC feed. Washing the extracted oil with water removed only modest amounts of metals. It was found that washing the algae with water first, and then doing solvent extractions, resulted in oils with metals levels low enough for co-feeding to an FCC unit at a level of 2%. The oil yields by mass from the starting algae from this route were 21% for ethanol solvent, and 10% for heptane solvent. If an FCC unit were completely dedicated to bio-feeds without the necessity of co-processing petroleum feedstocks, the unit might operate with a different catalyst and different set of operating constraints, but that is beyond the scope of this study.

Hydrocarbon liquid production via the bioCRACK process and catalytic hydroprocessing of the product oil

Combination of liquid phase pyrolysis based bioCRACK biomass liquefaction and catalytic hydroprocessing for Hydrocarbon production.

Heavy oil hydroprocessing: effect of nanostructured morphologies of MoS2 as catalyst

Five morphologically different nanostructured molybdenum disulfide (MoS2) samples were prepared, namely: nanoparticles, nanorods, nanoplatelets, nanoflowers and porous. These structures were characterized using X-ray diffraction and scanning electron microscope analyses. Afterwards, the up gradation of heavy oil was carried out in the presence of aforementioned nanostructures of molybdenum disulfide as catalysts. The results of catalytic and non-catalytic hydro-processing were compared. It was found that catalytic hydro-processing, due to lower sulfur contents, led to a more efficient and environmental friendly procedure as compared to non-catalytic hydro-processing. Furthermore, aromaticity, aromaticity condensation and branchiness index were also determined. In addition, nuclear magnetic resonance analyses were presented for the product of catalytic hydroprocessing. The nanoparticle morphology of molybdenum disulfide, catalyst, exhibited better result, due to its higher surface area, as compared to other morphologies of molybdenum disulfide catalysts, i.e., nanorods, nanoplatelets nanoflowers and porous structures.

Hydrocarbon Liquid Production from Biomass via Hot-Vapor-Filtered Fast Pyrolysis and Catalytic Hydroprocessing of the Bio-oil

Hot-vapor-filtered bio-oils were produced from two different biomass feedstocks, oak and switchgrass, and the oils were evaluated in hydroprocessing tests for the production of liquid hydrocarbon products. Hot-vapor filtering reduced bio-oil yields and increased gas yields. The yields of fuel carbon as bio-oil were reduced by 10% by hot-vapor filtering for both feedstocks. The unfiltered bio-oils were evaluated alongside the filtered bio-oils using a fixed-bed catalytic hydrotreating test. These tests showed good processing results using a two-stage catalytic hydroprocessing strategy. Equal-sized catalyst beds, sulfided Ru on a C catalyst bed operated at 220 °C and sulfided CoMo on an Al2O3 catalyst bed operated at 400 °C were used with the entire reactor at 10 MPa operating pressure. The products from the four tests were similar. The light-oil-phase product was fully hydrotreated, so that nitrogen and sulfur were below the level of detection, while the residual oxygen ranged from 0.3 to 2.0%. The density...

Reactor Design of Microwave Assisted Demetallization of Heavy Crude Oil

In the recent years with the deeper exploiting of world-wide crude oil, the heavy and poor trend of which is aggravating, inducing the metal contents in the oil increasing rapidly. Vanadium (V) and nickel (Ni) are the most harmful metals to petroleum processing among these metals, which mainly displays poisonous effect to the catalysts of Fluid Catalytic Cracking (FCC) and hydrogenation. The commonly used technologies to remove these metals can be classified into physical method, chemical method and catalytic hydroprocessing method. Hydrodemetallization (HDM) is widely employed in industry. However, the products of HDM reactions can accumulate in the catalyst pores, causing the formation of deposits which end up obstructing those pores irreversibly, blocking access to the catalyst sites and leading to a progressive loss of catalytic activity. Thus the removal of nickel and vanadium from crude oil has become a challenge in petrochemical processing.This work focuses on these metals removal by using microwave heating technology. A suitable reactor was first developed through numerical simulation technology using COMSOL. It was found that the reactor with a radius of 20 mm shows good coupling with microwaves, and the optimized loading height achieved is 40 mm. Experiments of demetallization were then conducted for Venezuela crude oil using this reactor, the maximum removal rate of 72.4 % and 76.8 % were obtained for Ni and V respectively. However, by using this batch reactor, the temperature distribution is non-uniform within the treated material, a continuous system were therefore developed to overcome the un-even electric field distribution. The reactor was designed as a cylinder with the length of 500 mm, and different crude oil flow rates were simulated, good demetallization rate can be achieved using the same microwave operating conditions.

Study on the hydrotreatment of C9 aromatics over supported multi-metal catalysts on γ-Al2O3

With the dramatic increasing of economy, the conflict between the lack of petroleum resource and sharply increasing demand for gasoline and diesel has restricted the continuous development of economy and energy of our world. The catalytic conversion of C9 aromatics into clean fuel was studied in our laboratory using hydrotreating catalysts which were prepared by new synthesis technologies that combine vacuum-impregnation and temperature-programmed calcinations. Characterization results indicate that these catalysts have a high surface area, and the activity sites dispersed well on the supporter. Hydrogenation performance of reaction conditions was carried out in two-stage fixed beds. Products of gasoline (<180 °C) and diesel (180–360 °C) fractions were separated from intermediate products via distillation, and the analysis results demonstrate that S/N content, density, and viscosity decreased. However, the H/C molar ratio increased. The main reactions of isomerization, disproportionation, and dealkylation occurred during the conversion of C9 aromatics and the activity order accorded the mechanism of carbenium ion reaction. This study indicates that C9 aromatics could be considerably upgraded through catalytic hydroprocessing to high-quality fuel in the presence of high-performance catalysts and appropriate reaction conditions. Thus, they are promising catalytic technologies and materials. Furthermore, the products could substitute gasoline and diesel partly.

Single stage hydroprocessing of pyrolysis oil in a continuous packed‐bed reactor

Raw bio‐oil cannot be combusted as transportation fuel directly because of its high acidity, high water content, lower heating value, and variable viscosity over time. Therefore, bio‐oil should be chemically converted to a more stable liquid product before subjecting it to hydrodeoxygenation (HDO) conditions. This research article focuses on catalytic hydroprocessing of pretreated bio‐oil (PTBO) in a single stage reaction using various catalyst compositions in a packed‐bed reactor. Four catalysts, a conventional hydrotreating catalyst (CoMo/γ‐Al2O3), an Fe‐Cr based mixed oxide catalyst, an FeW/Si‐Al catalyst, and a 1:2 mixture of Ru/γ‐Al2O3 and Ni/Si‐Al catalyst, were tested for conversion of the PTBO to mixed liquid hydrocarbons at 350–400°C, 1500 psig hydrogen pressure, and at a liquid hourly space velocity (LHSV) of 0.2–0.3 h−1. Liquid products produced from the HDO treatments were analyzed for properties such as acid value, heating value, elemental analysis, water content, and chemical characterization. The conventional hydrotreating catalyst, CoMo/γ‐Al2O3, performed the best among the four catalysts employed to reduced the acid value to 2 mg KOH/g and oxygen content to 0.1% while improving the heating value to 43 MJ/kg of the liquid product. The detailed hydrocarbon analysis of the reduced CoMo/γ‐Al2O3 upgraded hydrocarbon mixture showed the presence of olefins, iso‐paraffins, followed by naphthenes and aromatics. Simulated distillation results indicated that the liquid fuel had a boiling point range of 69–304°C, indicating the presence of petroleum equivalents of 50% gasoline (38–170°C), 30% jet fuel (170–250°C), and 20% diesel (250–304°C) range hydrocarbons. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 726–731, 2014

Quality and sustainability comparison of one- vs. two-step catalytic hydroprocessing of waste cooking oil

A quality and sustainability comparison of the catalytic hydroprocessing of waste cooking oil (WCO) using a single-step (hydrotreatment) vs. a two-steps (hydrotreatment+isomerization) approach was conducted. The product fuel properties from both approaches were excellent, abiding by the newly established CEN TS 15940:2012 standard for Hydrotreated Vegetable Oil (HVO) fuels. The only consideration of the single-step product regarding its increased cold flow properties was addressed by the second isomerization step or by blending with fossil diesel (<10% v/v). Furthermore, the environmental impact of the examined one- and two-step WCO catalytic hydroprocessing was evaluated via Life Cycle Assessment (LCA), quantifying the associated greenhouse gas (GHG) emissions. LCA indicated a reduced sustainability of the two-step product as compared to the one-step product, due to the additional energy and hydrogen requirements of the second isomerization step.

Catalytic Hydroprocessing of Furfural to Cyclopentanol Over Ni/CNTs Catalysts: Model Reaction for Upgrading of Bio-oil

A series of nickel-based catalysts with HNO3-pretreated CNTs as support (x% Ni/CNTs, x represents the Ni loading amount) were synthesized using impregnation method, which were successfully applied for the upgrading of model compound (furfural) in bio-oil. Effects of nickel loading amount, reaction temperature, reaction time and hydrogen pressure on conversion of furfural as well as selectivity for cyclopentanol were investigated systematically. The conversion of furfural over 30 wt% Ni/CNTs was up to 96.5 % with a yield of 83.6 % toward cyclopentanol, when the reaction was carried out at 140 °C with a initial H2 pressure of 5.0 MPa. The features of the Ni/CNTs catalysts were investigated via XRD, XPS, TEM. .

Catalytic hydroprocessing of fast pyrolysis bio-oil from Chlorella

Catalytic hydroprocessing of the bio-oil obtained through fast pyrolysis of Chlorella was carried out in a bench-scale continuous-flow fixed-bed reactor equipped with a Ni-Co-Pd/γ-Al2O3 catalyst. The effects of the hydrogenation temperature and the H/oil molar ratio on the moisture content, calorific value, viscosity and cetane number of the refined bio-oils were investigated at the pressure of 2×106 Pa, It was shown that the yield of the refined oil reached 89.6%, and the calorific value and cetane number were increased by 17.94% and 71.2% respectively, while the viscosity was decreased by 66.32% at the temperature of 300°C, the pressure of 2×106 Pa and the H/oil molar ratio of 120. The elemental analysis and GC-MS analysis results of the bio-oil before and after hydrogenation show that the H/C atomic ratio was increased from 1.55 to 1.97, while the oxygen, nitrogen and sulfur contents were significantly decreased. The deoxidation degree reached 80.46%. The amounts of organic acids, esters, ketones and aldehyde in the refined oils were obviously decreased, while those of alcohols and alkanes were markedly increased.

Hydroprocessing Bio-Oil and Products Separation for Coke Production

Fast pyrolysis of biomass can be used to produce a raw bio-oil product, which can be upgraded by catalytic hydroprocessing to hydrocarbon liquid products. In this study, the upgraded products were distilled to recover light naphtha and oils and to produce a distillation residue with useful properties for coker processing and production of a renewable low-sulfur electrode carbon. For this hydroprocessing work, phase separation of the bio-oil was applied as a preparatory step to concentrate the heavier, more phenolic components, thus, generating a more amenable feedstock for residue production. Low residual oxygen content products were produced by continuous-flow catalytic hydroprocessing of the phase separated bio-oil.

Heavy oil upgrading at moderate pressure using dispersed catalysts: Effects of temperature, pressure and catalytic precursor

A study of the influence of reaction parameters (reaction temperature, pressure and catalytic precursor) on the upgrading of Maya heavy oil under low pressure and moderate temperature under slurry conditions is presented. The behavior of the purely thermal hydrotreating system was first characterized to have a basis for distinguishing the effect of incorporating a catalyst in further hydrotreatings. The distillation curves of liquid product were obtained by thermo gravimetric analysis (TGA), ASTM standards were used for evaluation of API gravity and content of asphaltenes and carbenes–carboids. The separated asphaltenes were analyzed by XRD and C13 NMR techniques. The effect of temperature, catalytic precursor and pressure (800 and 960psi) of process were studied. The study of thermal hydrotreating showed that 390°C and 400°C were promising temperatures for catalytic hydroprocessing and increasing pressure approximately 100psi promoted the improvement of light liquid fractions at the expense of the heavy and residua fractions. The use of catalytic precursors at 400°C in concentrations of 330ppm of Mo increased gasoline production without producing more solids but did not result in the improvement of the liquid yield in comparison to the homologous thermal hydrotreatment. The liquid yield was improved either hydrotreating at 390°C or at 400°C with 1000ppm Mo as catalyst.