Existing Refinery Infrastructure Research Articles

Reduction of fossil CO2 emissions of engine fuels by integration of stabilized bio-oil distillation residue to a crude-oil refinery hydrocracking process

Utilization of waste lignocellulosic biomass to produce high-quality fuels with renewable carbon content using existing refinery infrastructure is an important step towards carbon neutrality. Direct hydroprocessing of pyrolysis bio-oil to liquid biofuels is technically challenging due to its wide fractional and complex chemical composition that requires harsh reaction conditions associated with extensive biocarbon loss to the gaseous products. We have proposed a novel bio-oil hydroprocessing strategy based on 1) bio-oil hydrotreatment (stabilization), 2) fractionation of the stabilized bio-oil and 3) co-processing of the fractions in appropriate refinery processes. In this work, we focus on the co-processing of the stabilized bio-oil distillation residue (SBDR, b.p. 360+°C) with vacuum gas-oil (VGO) in a hydrocracking fixed bed reactor under conventional conditions. This allowed us to maximize biogenic carbon content (92%) in the liquid transportation fuels as confirmed by the distribution of 14C (obtained by Accelerator Mass Spectrometry) into the corresponding fractions. i.e. gases, naphtha, kerosene, diesel and distillation residue. Reduction of the fossil CO2 emission was 3 times higher for the naphtha fraction compared with E10 gasoline; 2.4 times higher for the diesel fraction compared with B7 diesel (7 vol% FAME). Detailed analysis of the products via GC × GC-TOFMS, 13C NMR, and FTIR together with the standardized methods demonstrated that fuel distillates met requirements for conventional fuels with only negligible effect of the SBDR on physicochemical properties of products and catalyst stability. This shows that the co-hydrocracking of SBDR is a suitable process to maximize liquid fuel production with increased biogenic carbon content.

Comparison of co-refining of fast pyrolysis oil from Salix via catalytic cracking and hydroprocessing

Lignocellulosic biomass from energy crops, i.e., short rotation coppice willows such as Salix spp., can be used as feedstock for production of transportation biofuels. Biomass conversion via fast pyrolysis followed by co-refining with fossil oil in existing refinery infrastructure could enable a fast introduction of large-scale production of biofuels. In this study, Salix was first liquefied using ablative fast pyrolysis in a pilot scale unit. The resulting pyrolysis oil, rich in oxygenates, was thereafter co-refined in 20 wt% ratio with fossil feedstock using two separate technologies, a fluidized catalytic cracking (FCC) laboratory unit and a continuous slurry hydroprocessing pilot plant.In the FCC route, the pyrolysis oil was cracked at 798 K using a commercial FCC catalyst at atmospheric pressure, while in the hydroprocessing route, the oil was processed at 693 K and a hydrogen pressure of 15 MPa in the presence of an unsupported molybdenum sulfide catalyst. Both routes resulted in significant deoxygenation (97 wt% versus 93 wt%). It is feasible to co-refine pyrolysis oil using both methods, the main difference being that the hydroprocessing results in a significantly higher biogenic carbon yield from the pyrolysis oil to liquid and gaseous hydrocarbon products (92 wt%) but would in turn require input of H2. In the cracking route, besides the liquid product, a significant part of the biogenic carbon ends up as gas and as coke on the catalyst. The choice of route depends, among other factors, on the available amount of bio-oil and refining infrastructures.

Production of green jet fuel from furanics via hydroxyalkylation-alkylation over mesoporous MoO3-ZrO2 and hydrodeoxygenation over Co/γ-Al2O3: Role of calcination temperature and MoO3 content in MoO3-ZrO2

Green biofuels are equivalent to hydrocarbon-based motor fuels and compatible with existing refinery infrastructures and combustion engines. Therefore, sustainable production of green biofuels is essential to circumvent the construction of expensive biorefinery infrastructures. This study thus presents the production of green jet fuel from biomass-derived furanic compounds via hydroxyalkylation-alkylation (HAA) reaction coupled with hydrodeoxygenation (HDO) of the C15 biofuel precursor. MoO3-promoted ZrO2 is a promising solid acid catalyst with excellent thermal stability. The HAA reaction of 2-methylfuran with furfural was thus investigated over a novel MoO3-promoted mesoporous ZrO2 catalyst. This work elucidated the role of calcination temperature and MoO3 loading on the structural variation of MoO3-promoted mesoporous ZrO2 and the evolution of acid sites. The highest acid density and consequently best catalytic performance was observed at 873 K calcination temperature with 20 wt% MoO3 loading. About 85 % 2-methylfuran conversion was achieved over 1.25 g of this optimum catalyst at 2:1 2-methylfuran/furfural mole ratio, 323 K, and 5 h. The HAA reaction was further investigated at various reaction temperatures, catalyst loadings, and 2-methylfuran/furfural mole ratios to obtain optimum reaction conditions. HDO of biofuel precursor was examined over Co/γ-Al2O3 catalyst at various reaction temperatures, initial hydrogen pressure, and Co metal loading on γ-Al2O3 to understand the reaction mechanism and identify the optimum reaction conditions. HDO of biofuel precursor progressed through successive furan ring saturation and opening reactions, followed by a combination of HDO, decarbonylation, and cleavage of tertiary-carbon bonds. C9-C15 alkanes were observed as products, with C11 and C14 hydrocarbons being dominant at 573 K and 30 bar. The elevated hydrogen pressure and reaction temperature boosted the conversion of oxygen-containing intermediate compounds at the cost of CC cracking reactions. The conversion of oxygen-containing intermediate compounds was enhanced with rising Co metal loading on γ-Al2O3 up to 20 wt% due to the enhancement of metal dispersion.

Operational optimization of co-processing of heavy oil and bio-oil based on the coordination of desulfurization and deoxygenation

Co-processing of heavy oil and bio-oil in an existing refinery has been proposed to reduce the production cost of bio-fuels by using the existing refinery infrastructures. Considering the high sulfur content in heavy oil and high oxygen content in bio-oil, an operational optimization model integrated impurity distributions of fluid catalytic cracker (FCC) and hydrogenation reaction kinetics of hydrotreating (HDT) unit is built to lower the utility cost of co-processing process based on coordination of desulfurization and deoxygenation. Polynomial fitting is adopted to reduce the non-linearity of kinetics and a solving strategy is proposed to guarantee the accuracy. Results indicate that the total utility cost of the co-processing process reduces by 6.7% by optimizing impurity removal degrees of all units in the co-processing process. The impurity removal of FCC should not be ignored as it can reduce more than 28% impurity of the total impurity from feed oil without consuming hydrogen gas. The advantages of integrating FCC impurity distributions and hydrogenation reaction kinetics into the proposed model are also discussed. It is necessary to integrate FCC and kinetics when optimizing the co-processing process or FCC and HDT units in refinery.

Techno-economically-driven identification of ideal plant configurations for a new biomass-to-liquid process – A case study for Central-Europe

The conversion of agricultural waste materials such as bark or straw into 2nd generation biofuels constitutes an auspicious way to meet part of the future fuel demand in a sustainable way. The number of possible production routes is diverse, and the techno-economic analyses of these routes have been conducted in very different ways. The route involving gasification, gas purification, and a subsequent Fischer-Tropsch synthesis enables the production of hydrocarbons that achieve current fuel standards after upgrading in the existing refinery infrastructure. To evaluate a promising biomass-to-liquid process, a methodology is presented that incorporates economic constraints into the process design, allowing identification of a regionally optimal process design. The production costs of the new concepts are estimated by setting up a detailed flowsheet simulation in AspenPlus® based on experimental data from the successful demonstration runs of the EU-Project COMSYN. In addition, an existing techno-economic evaluation methodology incorporated into the in-house software tool TEPET (Techno-Economic Process Evaluation Tool) has been extended to evaluate the processes’ performance in different European regions and to include transportation and refining costs. The approach enables the identification of regional sweet spots shown on a map for Central-Europe, indicating production costs and favorable process design for each region. Furthermore, the results of an automated mapping for the optimal process design depending on the heat and electricity market are presented. The performed analyses show that the techno-economic evaluation tends to expand the technology in regions with low feedstock costs, while the optimal process design is defined by the regional heat and electricity market. In this work, net production costs of less than 1.12 €2019/lbiofuel were determined for regions in Hungary, Poland and Slovakia.

Continuous Slurry Hydrocracking of Biobased Fast Pyrolysis Oil

Co-refining of fast pyrolysis bio-oil together with fossil oil in existing refinery infrastructure is an attractive and cost-efficient route to conversion of lignocellulosic biomass to transportation fuel. However, due to large differences in properties between the two oils, special notice is needed to reduce process-related issues. Here, fast pyrolysis bio-oil produced from lignocellulosic biomass was co-refined with vacuum gas oil at a 20:80 weight ratio in continuous operation in a pilot-scale slurry hydrocracker in order to investigate the impact of process parameters on product quality and process performance. Mass balances together with product characterization were used to investigate product yields, product composition, and hydrodeoxygenation. Best conversion and hydrodeoxygenation of the fast pyrolysis bio-oil was achieved using an unsupported catalyst loading of 900 ppm Mo with either a low temperature (410 °C) and long residence time (2 h) or higher temperature (435 °C) and shorter residence time (1 h). These settings resulted in about 94% hydrodeoxygenation but also led to highest yield of biogenic carbon to gas phase (40–43 wt %) and lowest yield of biogenic carbon to oil fractions (53–56 wt %) as well as the water fraction (3–5 wt %). Successfully, coke yield remained low at around 0.07–0.10 wt % for all performed runs, which was comparable to the insoluble particle content in the feed due to the presence of particles in the untreated fast pyrolysis bio-oil. Co-processing pyrolysis oil with fossil oil in a slurry hydrocracker seems to be a robust process with regard to coke formation, which should lead to reduced plugging issues compared to fixed bed hydrotreaters. Although this study gives a brief understanding of the effect of process parameters on the processing of fast pyrolysis bio-oil, further research is required to find optimal process parameters and to fully comprehend the possibilities and limitations for production of transportation fuels from fast pyrolysis bio-oil using this technology.

Design and Integration of Bio-Oil Co-Processing with Vacuum Gas Oil in a Refinery

Due to the climate change and the strong dependence on fossil fuels, biomass-derived liquid transportation fuels and energy products have been proposed to deal with such situations. Usually, the prices of the bio-diesel and bio-gasoline are much higher than those of fossil fuels. The co-processing of bio-oil and vacuum gas oil (VGO) in a fluid catalytic cracker of a refinery has been proposed to utilize the existing refinery infrastructures and decrease the prices of bio-fuels. However, the integration between the bio-oil production and the existing refinery is not clear. In this work, a superstructure model is built to design and optimize the co-processing process with minimum total annual cost which features to select the optimal bio-oil production technology (fast pyrolysis or catalytic pyrolysis) and obtain the optimal integration scheme. Furthermore, the impacts of the prices of biomass and hydrogen, the bio-oil co-processing ratio on the economics of the co-processing system are also investigated. The optimal integration scheme of the co-processing of bio-oil and VGO can be obtained by solving the proposed model.

Techno-economic analysis of bio-oil co-processing with vacuum gas oil to transportation fuels in an existing fluid catalytic cracker

The co-processing of bio-oil and vacuum gas oil (VGO) in an existing fluid catalytic cracker (FCC) for productions of gasoline and diesel has been proposed and regarded as a possible technique to realize partial replacement of fossil fuels. A techno-economic analysis (TEA) was conducted to evaluate the economics of two co-processing scenarios, the co-processing of VGO and the fast pyrolysis oil or the catalytic pyrolysis oil. As revealed by the TEA results, the capital cost can be reduced significantly by using the existing refinery infrastructures and the minimum gasoline selling prices under the two scenarios were $2.63 and $2.60 per gallon respectively, which can be competing with that of petroleum-derived gasoline. As shown by the sensitivity analysis, the gasoline price was extremely sensitive to the fluctuations of the fuel yields, VGO and diesel prices, and FCC capability. Therefore, the co-processing technique to produce bio-transportation fuels can be identified as a partial replacement for the petroleum-derived fuels.

Design and optimization of bio-oil co-processing with vacuum gas oil in a refinery

The prices of the bio-diesel and bio-gasoline are normally significantly high when compared to the petroleum-derived fuels. The co-processing of bio-oil and vacuum gas oil in a fluid catalytic cracker (FCC) has been proposed to utilize existing refinery infrastructures while lowering bio-fuel prices. Nonetheless, the integration of the bio-oil production and the existing refinery remains unknown. In this work, a superstructure model is proposed to design and optimize the co-processing process by selecting the optimal biomass feedstock and the bio-oil production process (fast pyrolysis or catalytic pyrolysis). Furthermore, the impacts of the FCC processing capability and bio-oil co-processing ratio on the economics as well as the selection of bio-oil production process are also investigated. As revealed by the results of two scenarios, pulpwood is the optimal biomass feedstock and the fast pyrolysis ought to be selected for producing bio-oil when its co-processing ratio and the FCC processing capability are both relatively high.

Catalytic cracking of fast and tail gas reactive pyrolysis bio-oils over HZSM-5

Hydrodeoxygenation (HDO) of pyrolysis oil is well understood as an upgrading method; however, the high processing pressures associated with it alone justify the exploration of alternative upgrading solutions, especially those that could adapt pyrolysis oils into the existing refinery infrastructure. Catalytic cracking is one such alternative industrial practice that can be carried out at near-atmospheric pressure using zeolite-based FCC catalysts. The present study focuses on the catalytic cracking of pyrolysis oil of different starting compositions over HZSM-5 to inform the extent of upgrading in the liquid phase. After establishing a catalyst bed temperature of 500°C as the optimum operating condition with regard to deoxygenation and yield of mono-aromatics in the products obtained, the performances of conventional pyrolysis and tail gas reactive pyrolysis (TGRP) bio-oils as starting liquids for the cracking were compared. The results indicate that the formation of naphthalenes was favored, while the formation of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds was slightly depressed in the case of the TGRP oil. We attribute this finding to the formation of naphthalenes from BTEX molecules already found in the TGRP oil. Subsequent reuse of the catalysts showed that the cracking of TGRP bio-oil exhibited slightly greater deactivation after a third cycle, likely due to the increased formation of naphthalenes and coke which can block HZSM-5 pores. The results obtained from this study will help determine the issues that need to be addressed when developing a catalytic cracker with HZSM-5 for regular pyrolysis oil and TGRP oil.

Corrosion of stainless steels in the riser during co-processing of bio-oils in a fluid catalytic cracking pilot plant

Co-processing of bio-oils with conventional petroleum-based feedstocks is an attractive initial option to make use of renewable biomass as a fuel source while leveraging existing refinery infrastructures. However, bio-oils and their processing intermediates have high concentrations of organic oxygenates, which, among their other negative qualities, can result in increased corrosion issues. A range of stainless steel alloys (409, 410, 304L, 316L, 317L, and 201) was exposed at the base of the riser in a fluid catalytic cracking pilot plant while co-processing vacuum gas oil with pine-derived pyrolysis bio-oils that had been catalytically hydrodeoxygenated to ~2 to 28% oxygen. A catalyst temperature of 704°C, a reaction exit temperature of 520°C, and total co-processing run times of 57–75h were studied. External oxide scaling 5–30μm thick and internal attack 1–5μm deep were observed in these short-duration exposures. The greatest extent of internal attack was observed for co-processing with the least stabilized bio-oil, and more so for types 409, 410, 304L, 316L, 317L stainless steel than for type 201. The internal attack involved porous Cr-rich oxide formation, associated with local Ni-metal enrichment and S-rich nanoparticles, primarily containing Cr or Mn. Implications for alloy selection and corrosion are discussed.

Integration of biomass catalytic pyrolysis and methane aromatization over Mo/HZSM-5 catalysts

The development of an effective process to convert bio-oil into intermediate platforms that are compatible with the existing refinery infrastructure is highly needed. To overcome the high cost of hydrogen consumption in conventional bio-oil upgrading processes, this paper reports a novel process that converts three major biomass constituents (cellulose, hemicellulose and lignin) directly into liquid fuels via pyrolysis in the presence of methane over molybdenum impregnated HZSM-5 catalysts. The carbon yield of total aromatics from lignin increased from 12.80 to 15.13% when pyrolysis atmosphere switched from helium to methane in the presence of HZSM-5 support. However, methane was not effective in improving the aromatics yield from cellulose and hemicellulose in the presence of Mo-modified HZSM-5 catalysts. The molybdenum impregnated catalyst was found to promote deoxygenation of lignin-derived phenols. The carbon yield of polyaromatics from lignin was 5.47% in the presence of HZSM-5 support under methane, compared to 2.61% that obtained in the presence of Mo2C/HZSM-5.

A perspective on oxygenated species in the refinery integration of pyrolysis oil

Pyrolysis offers a rapid and efficient means to depolymerize lignocellulosic biomass, resulting in gas, liquid, and solid products with varying yields and compositions depending on the process conditions. With respect to manufacture of “drop-in” liquid transportation fuels from biomass, a potential benefit from pyrolysis arises from the production of a liquid or vapor that could possibly be integrated into existing refinery infrastructure, thus offsetting the capital-intensive investment needed for a smaller scale, standalone biofuels production facility. However, pyrolysis typically yields a significant amount of reactive, oxygenated species including organic acids, aldehydes, ketones, and oxygenated aromatics. These oxygenated species present significant challenges that will undoubtedly require pre-processing of a pyrolysis-derived stream before the pyrolysis oil can be integrated into the existing refinery infrastructure. Here we present a perspective of how the overall chemistry of pyrolysis products must be modified to ensure optimal integration in standard petroleum refineries, and we explore the various points of integration in the refinery infrastructure. In addition, we identify several research and development needs that will answer critical questions regarding the technical and economic feasibility of refinery integration of pyrolysis-derived products.

Hydrodeoxygenation and hydrodesulfurization co-processing over ReS2 supported catalysts

The hydrodeoxygenation (HDO) of bio-oil can be undertaken together with the hydrodesulphurization (HDS) of gas–oil in order to use already existing refinery infrastructures and to directly obtain a partially bio-sourced fuel. In this work, the HDO of 2-methoxyphenol (guaiacol) and the HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out over ReS2 catalysts supported on SiO2 and γ-Al2O3. It was observed in the co-processing reactions that the total and HDS conversion rates of 4,6-DMDBT decreased compared to the rates obtained in separate reactions over both catalysts, while the total conversion rate of guaiacol increased under the same conditions. This behavior is probably due to the competitive adsorption between 4,6-DMDBT and 2-methoxyphenol occurring on the same active sites on the catalysts. On the other hand, in co-processing reaction the HDO rate decreased 1.4 times over the ReS2/SiO2 catalyst while it increased 1.9 times over ReS2/Al2O3 catalyst. The observed behavior with the ReS2/Al2O3 catalyst was explained in terms of competitive effects and inhibition of acid sites on this catalyst: the less availability of acid sites disfavored the demethylation route which led to the direct conversion of guaiacol to phenol via demethoxylation, and thus enhancing the HDO rate.