Primary Gas Research Articles

Catalytic pyrolysis of biomass to produce aromatic hydrocarbons in a cascade dual-catalyst system: Design of red mud based catalyst assisted by the analysis of variance

Theoretical and experimental study on the catalytic pyrolysis of rape straw was carried out for the production of aromatic hydrocarbons using the composite red mud (RM) and zeolite HZSM-5 catalyst as the combined catalysts. In the orthogonal tests and analysis of variance (ANOVA), it was originally established that Fe2O3 and CaO acted as the active metal oxides in the red mud, which played the notable role in the production of benzene, toluene and xylene (BTX) as hydrocarbon fuels. Subsequently, the physicochemical property of the Fe2O3 and CaO loaded red mud (Fe2O3-RM and CaO-RM) was investigated and their performance in the catalytic pyrolysis of rape straw combined with HZSM-5 were investigated. It was revealed that the further cracking of the primary pyrolysis gas was promoted with more active Fe2O3 involved, and the heavy component was converted into the light fraction entering HZSM-5 for deoxygenation and aromatization to produce aromatic hydrocarbons. The yield of BTX over Fe2O3-RM was boosted by 10.15 wt% compared with the original red mud catalyst, while that of BTX was further promoted to 11.37 wt% over the composite red mud catalyst with 6% CaO loading. In addition to the strong bond-breaking performance of CaO, calcium carboxylate was easily generated and then decomposed to form CaCO3 and ketones, and then BTX were produced from ketones over HZSM-5 by deoxygenation and aromatization. In this study, the high-performance red mud-based catalysts was designed and utilized in the thermochemical conversion of biomass, providing a potential way for the utilization of two solid wastes, rape straw and red mud to produce hydrocarbon fuels in a high-valued way.

Influence of elevated temperature exposure on the interfacial shear strength capacity of binary blended high strength self-compacting geopolymer concrete

The development of sustainable infrastructure is a serious issue faced by modern society. Portland cement is one of the common ingredients in concrete, which influences construction activities. The major issue with the employment of cement in civil-based works is that it is responsible for carbon dioxide emission (CO2-e), the primary greenhouse gas responsible for global warming. Alternative to cement-based concrete, geopolymer concrete (GPC) employs zero cement for concrete production, leading to a reduction in CO2-e. In the case of mass concreting, interface/joints are developed, which are found to be the possible failure spots of brittle fracture. Concrete with different grades (strength) may interface, or other building materials, such as reinforcing materials. The interfacial bond strength has to be examined to ensure the homogeneity of the composite structures. The employment of shear ties at the interface ensures homogeneous behaviour. Moreover, a higher number of shear ties in the shear zone increases the cost of production. The interfacial shear strength (ISS) parameters will be miserably damaged in the concrete structures subjected to fire accidents, which might depend on the intensity of temperature exposure and its duration. The current study investigates the ISS of the High Strength Self-compacting geopolymer concrete (HSGC) in the interface of push-off samples. SCGC was made using binary blended composites, which comprised Fly Ash (FA), Metakaolin (MK), and Ground Granulated Blast Furnace Slag (GGBFS) as precursor materials. The work highlights the need to comprehend the reduction in shear strength of SCGC subjected to high temperatures. The fresh properties of the SCGC composites strictly adhered to the EFNARC guidelines. The SCGC composites, after their curing period, were exposed to 821 ℃, 925 ℃, 986 ℃, and 1029 ℃ following ISO 834 guidelines. Residual mechanical properties were examined after being cooled to room temperature.

Investigation of gas transport resistance in fuel cell catalyst layers via hydrogen limiting current measurements of CO-covered catalyst surfaces

The efficiency of fuel cell operation at high power strongly affects the total cost of ownership of fuel cell vehicles. Gas transport resistance at the cathode strongly suppresses efficiency during high-power operation. The resistance comprises Knudsen diffusion resistance in pores formed among the primary carbon aggregates and local gas transport resistance. The former is independent of the electrochemically active Pt surface area per geometrical electrode area (roughness factor: RF). The latter is proportional to the inverse of RF. Separate identification of these resistances in actual catalyst layers remains challenging because of experimental limitations. Herein, we propose a method that can identify the RF-dependent and RF-independent resistances separately using a single sample. RF can be controlled by partially covering the Pt surface by CO. The gas transport resistance can be ascertained from the hydrogen limiting current. Measuring the hydrogen limiting current at controlled CO coverages allows separate identification of the resistances. The RF-dependent resistance is separable further into ionomer/Pt interfacial resistance and permeation resistance through the ionomer thin film by combining the obtained ionomer-to-carbon weight ratio dependence of each resistance component with structural and electrochemical analyses. The separate resistances show the ionomer/Pt interfacial resistance to be dominant in the catalyst layer.

Primary N2-He gas field formation in intracratonic sedimentary basins.

Helium, nitrogen and hydrogen are continually generated within the deep continental crust1-9. Conceptual degassing models for quiescent continental crust are dominated by an assumption that these gases are dissolved in water, and that vertical transport in shallower sedimentary systems is by diffusion within water-filled pore space (for example, refs. 7,8). Gas-phase exsolution is crucial for concentrating helium and forming a societal resource. Here we show that crustal nitrogen from the crystalline basementalone-degassing at a steady state in proportion to crustal helium-4 generation-can reach sufficient concentrations at the base of some sedimentary basins to form a free gas phase. Using a gas diffusion model coupled with sedimentary basin evolution, we demonstrate, using a classic intracratonic sedimentary basin (Williston Basin, North America), that crustal nitrogen reaches saturation and forms a gas phase; in this basin, as early as about 140 million years ago. Helium partitions into this gas phase. This gas formation mechanism accounts for the observed primary nitrogen-helium gas discovered in the basal sedimentary lithology of this and other basins, predicts co-occurrence of crustal gas-phase hydrogen, and reduces the flux of helium into overlying strata by about 30 per cent because of phase solubility buffering. Identification of this gas phase formation mechanism provides a quantitative insight to assess the helium and hydrogen resource potential in similar intracontinental sedimentary basins found worldwide.

Rapid Fabrication of Graphene Layers Over Polymeric Substrates Using Atmospheric Pressure Plasma Jet

In this article, we have employed an atmospheric pressure plasma jet (APPJ) system to produce graphene layers on polymeric substrates for large-area applications. Herein, the graphene layers are grown on four different polymers polyamide6 (PA-6), high-density polyethylene (HDPE), polypropylene (PP), and polyurethane (PU) using 200 W of 13.56-MHz RF power supply-induced APPJ with argon as primary gas in an open atmosphere. The formation of the graphene layers has been confirmed by Raman spectroscopy, X-ray diffraction (XRD), and field emission electron microscopy (FESEM). The optical emission spectra (OES) of the plasma plume have been taken to analyze the presence of active species. To ensure the thermal integrity of the polymers, thermal gravimetric analysis (TGA) has been done after the plasma treatment. Furthermore, the prepared samples have been tested to verify various properties of graphene, like hydrophobicity, electrical conductivity, bacteria detection, and antimicrobial properties. The hydrophobic nature of graphene has been tested by measuring the contact angle. The electrical conductivity has been measured using the four-probe method to find out the applicability of the graphene-coated substrates for flexible electronic applications. The electrochemical three-probe-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I$</tex-math> </inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$</tex-math> </inline-formula> characterization has been done for E. coli bacteria detection, and the antimicrobial activity of the prepared samples has also been analyzed.

Toward the realization of a primary low-pressure standard using a superconducting microwave resonator.

We describe a primary gas pressure standard based on the measurement of the refractive index of helium gas using a microwave resonant cavity in the range between 500Pa and 20kPa. To operate in this range, the sensitivity of the microwave refractive gas manometer (MRGM) to low-pressure variations is substantially enhanced by a niobium coating of the resonator surface, which becomes superconducting at temperatures below 9K, allowing one to achieve a frequency resolution of about 0.3Hz at 5.2GHz, corresponding to a pressure resolution below 3 mPa at 20Pa. The determination of helium pressure requires precise thermometry but is favored by the remarkable accuracy achieved by ab initio calculations of the thermodynamic and electromagnetic properties of the gas. The overall standard uncertainty of the MRGM is estimated to be of the order of 0.04%, corresponding to 0.2Pa at 500 and 8.1Pa at 20kPa, with major contributions from thermometry and the repeatability of microwave frequency measurements. A direct comparison of the pressures realized by the MRGM with the reference provided by a traceable quartz transducer shows relative pressure differences between 0.025% at 20kPa and -1.4% at 500Pa.

High Purity Hydrogen Separation with HT-PBI Based Electrochemical Pump Operation at 120 °C

Electrochemical Hydrogen Pumps (EHP) provide a unique highly efficient means of separating and compressing hydrogen with continuous steady-state operation. In this paper, we demonstrate the performance of a commercially available, polybenzimidazole (PBI) membrane based platform as a benchmark for ultra-high efficiency performance. A primary gas mixture of CO2 and H2 with a ratio of 4:1 respectively was selected to demonstrate the performance of EHPs with near theoretical Faradaic efficiency with negligible CO poisoning due to reverse water gas shift reaction (RWGS). It was found that humidification of the feed gas at room temperature improved polarization performance while also improving energy efficiency, thus reducing the need for a tightly controlled relative humidity of feed gas. A new perspective on EHP energy efficiency calculation methodology is also provided by including the cell heating requirement in the calculation. In this manner, an overall improvement to the energy efficiency of nearly 20% was realized by dropping the cell temperature to 120 °C while paying no significant penalty to electrochemical performance. Nearly 99.99% pure H2 and 99.93% pure CO2 were produced with a hydrogen yield of 99.34%.

Strategies for CO2 capture: positive and negative feature

Abstract Carbon dioxide is one of the primary greenhouse gases affecting climate change and global warming. Thus, capturing carbon dioxide (CO2) has always been a significant issue in the environmental industry. Numerous procedures have been used to remove acid and natural gas from the flue. This review aims to illustrate and discuss the primary CO2 capture technologies, such as adsorption, absorption, and membrane separation. Moreover, the development of every technology.

Effects of zinc on χ-Fe5C2 for carbon dioxide hydrogenation to olefins: Insights from experimental and density function theory calculations

Production of light olefins from CO 2 , the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO 2 emission on environment and to supply the value-added products from non-petroleum resource. However, development of robust catalyst with controllable selectivity and stability remains a challenge. Herein, we report that Zn-promoted Fe catalyst can boost the stable and selective production of light olefins from CO 2 . Specifically, the Zn-promoted Fe exhibits a highly stable activity and olefin selectivity over 200 h time-on-stream compared to the unpromoted Fe catalyst, primarily owing to the preservation of active χ-Fe 5 C 2 phase. Structural characterizations of the spent catalysts suggest that Zn substantially regulates the content of iron carbide on the surface and suppresses the re-oxidation of bulk iron carbide during the reaction. DFT calculations confirm that adsorption of surface carbon atoms and graphene-like carbonaceous species are not thermochemically favored on Zn-promoted Fe catalyst. Carbon deposition by C—C coupling reactions of two surface carbon atoms and dehydrogenation of CH intermediate are also inhibited. Furthermore, the effects of Zn on antioxidation of iron carbide were also investigated. Zn favored the hydrogenation of surface adsorbed oxygen atoms to H 2 O and the desorption of H 2 O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.

Thermal hazard risk and decomposition mechanism identification of 1-Hexyl-2,3-dimethylimidazolium nitrate: Combined thermal analysis experiment and DFT emulation

Ionic liquids are extensively used in pharmaceutical, chemical and aerospace fields, and sometimes used in high temperature environments. Investigating the pyrolysis hazard characteristics and mechanism of ionic liquids is significant. 1-Hexyl-2,3-dimethylimidazolium nitrate ([Hmmim][NO3]) as a new versatile ionic liquid has been systematically studied in this paper. The pyrolysis characteristics of [Hmmim][NO3] in different conditions are researched by using thermogravimetric analyzer, differential scanning calorimetry and accelerating rate calorimeter technologies. Main thermodynamic parameters, safety parameters, and reaction pattern of [Hmmim][NO3] pyrolysis process are acquired. The severity degree and possibility of [Hmmim][NO3] runaway reaction is evaluated, which may result in serious damage to the plant. The microscopic mechanism of [Hmmim][NO3] pyrolysis has been explored comprehensive utilization thermogravimetry-flourier transform infrared spectroscopy, thermogravimetric-photoionization mass spectrometry and quantum-chemical simulation. The primary noxious gas and reaction steps leading to the thermal hazards of [Hmmim][NO3] are confirmed. This research provides a theoretical basis for improving the intrinsic safety of [Hmmim][NO3] application and formulating corresponding safety preventive measures.

Transformation of nitrogen during solar pyrolysis of algae in molten salt

Molten salt pyrolysis of N-rich algae driven by concentrated solar energy is considered as an economical and environmentally friendly method to prepare N-doped value-added carbon. The transformation of nitrogen during the carbon production process by algae pyrolysis in molten Na2CO3-K2CO3 is investigated in-depth, which contributes to the utilization or treatment of nitrogen-containing products. Algae-N is mainly converted to gasN, and the gas-N yield increases as temperature rises, reaching 75.7 wt.% at 900 °C. Molten salt reduces the release temperature of all N-containing gas, captures 89.6% of HCN as CN−, and promotes the release of NH3 and NO. The char-N is dominated by pyrrole-N and quaternary-N at 800–900 °C due to the promotion of molten salt and higher temperature. The major contributors to the bio-oil-N yield are pentadecanenitrile, isoamyl cyanide, benzyl nitrile, styryl cyanide, pyrrole and indole. Nitriles and indoles are promising N-containing products in value-added carbon production, while NH3 and NO are primary pollution gas to be controlled.

Methane emissions from California dairies estimated using novel climate metric Global Warming Potential Star show improved agreement with modeled warming dynamics

IntroductionCarbon dioxide (CO2) and methane (CH4) are two of the primary greenhouse gases (GHG) responsible for global warming. The “stock gas” CO2 accumulates in the atmosphere even if rates of CO2 emission decline. In contrast, the “flow gas” CH4 has an e-folding time of about 12 years and is removed from the atmosphere in a relatively short period of time. The climate impacts of cumulative pollutants such as CO2 and short-lived climate pollutants (SLCP) such as CH4 are often compared using Global Warming Potential (GWP), a metric that converts non-CO2 GHG into CO2-equivalent emissions. However, GWP has been criticized for overestimating the heating effects of declining SLCP emissions and conversely underestimating the heating impact of increasing SLCP emissions. Accurate quantification of the temperature effects of different CH4 emissions scenarios is particularly important to fully understanding the climate impacts of animal agriculture, whose GHG emissions are dominated by CH4.MethodsA modified GWP metric known as Global Warming Potential Star (GWP*) has been developed to directly quantify the relationship between SLCP emissions and temperature change, which GWP cannot do. In this California dairy sector case study, we contrasted GWP- versus GWP*-based estimates of historical warming dynamics of enteric and manure CH4 from lactating dairy cattle. We predicted future dairy CH4 emissions under business-as-usual and reduction scenarios and modeled the warming effects of these various emission scenarios.ResultsWe found that average CO2 warming equivalent emissions given by GWP* were greater than those given by GWP under increasing annual CH4 emissions rates, but were lower under decreasing CH4 emissions rates. We also found that cumulative CO2 warming equivalent emissions given by GWP* matched modeled warming driven by decreasing CH4 emissions more accurately than those given by GWP.DiscussionThese results suggest that GWP* may provide a more accurate tool for quantifying SLCP emissions in temperature goal and emissions reduction-specific policy contexts.

Key stage and model of hydrocarbon accumulation of Ordovician reservoir in Gucheng area, Tarim Basin, China

The heterogeneity of deep carbonate reservoirs is strong, it is significant for exploration and development to clarify the key stages of oil and gas accumulation. Taking the Ordovician in the Gucheng area of Tarim Basin as an example, this paper systematically investigated the key stage and model of hydrocarbon accumulation using the data of the cores, thin sections, cathode luminescence tests, laser ablation U-Pb isotope geochronometry, bitumen reflectance, and fluid inclusion tests, and seismic interpretation. (1) The Tarim Basin mainly develops three sets of effective source rocks, namely the Cambrian Yuertusi Formation, Cambrian Moheershan Formation, and Mid-Lower Ordovician Heituwa Formation, which are concentrated in the slope-basin facies of eastern Tarim Basin. (2) The Gucheng area is located in a favorable paleo-structural position. The pathway system composed of vertical faults and lateral unconformities occurs in the paleo-uplift, which is critical for hydrocarbon migration and accumulation. (3) The laser in-situ U-Pb dating, distribution and genesis of reservoir bitumen, burial-thermal maturation history, and the homogenization temperature of fluid inclusions suggest that the multi-stage tectonic thermal events of the Caledonian and Hercynian stages result in key adjustment and modification to deep hydrocarbon accumulation. Due to magmatic hydrothermal activities, the Caledonian primary oil reservoir massively evolved into oil-cracking gas reservoirs and residual paleo-oil reservoirs. (4) The paleo tectonic-fluid effect plays an important factor controlling the development of the Ordovician reservoirs. The evolution of the hydrocarbon accumulation in Gucheng area can be divided into three stages, namely formation of primary oil and gas reservoirs, oil-cracking gas reservoirs, and adjustment, destruction and reforming of gas reservoirs. To sum up, the western and northern parts of the paleo-uplift with favorable source-reservoir-cap rock assemblage and less effects of hydrothermal activities are the favorable zones for hydrocarbon exploration in the Gucheng area, the Tarim Basin.

Comparative CO2 emissions of concrete and timber slabs with equivalent structural performance

Comparing the environmental impacts of building materials at the building level can be biased because a building design is optimized for a primary structural material. To achieve objective comparisons, this study compares the environmental impact of reinforced concrete (RC), cross-laminated timber (CLT), and timber-concrete composite (TCC) at the component level with equivalent structural performance. A slab was selected as the target structure member because its design does not consider lateral forces. Equivalent structural performance was defined as the minimum quantity of slab materials for comparable span and live load conditions. The functional unit for this study was defined as a 1 m2 slab. The system boundary covered the cradle-to-gate perspective, including raw material extraction, transportation, and manufacturing. The structural design method and material design values followed the Korean building code and standards. Environmental product declaration data developed in Korea were used to evaluate the carbon footprint. The CLT emitted 75 % less carbon dioxide, the primary greenhouse gases responsible for anthropogenic climate change, compared with RC regardless of conditions, while the TCC emitted 65 % less CO2, and its environmental impact improved as the span lengthened. The results also indicated that timber slabs are thinner than concrete slabs and can be structurally rational.

Generation of a low-temperature plasma in a nozzle to initiate ion-cluster reactions in jets of mixtures of methane with a buffer gas

We have considered the option of generating cluster ions directly at the nozzle by initiating an electric discharge. Here, a low-temperature plasma in the flow is formed as a result of the outflow of a partially ionized gas. Conditions for the formation of clusters in the presence of excited particles are provided downstream. To implement this generation option, a scheme for creating an effective discharge in the diffuser part of a supersonic nozzle was proposed and implemented. The diagnostic system of the LEMPUS-2 gas-dynamic facility was adapted to register processes in a supersonic flow of ionized gas with clusters. Molecular nitrogen, which is weakly condensing under experimental conditions, was used as the primary reference gas. The methods of molecular beam mass spectrometry were used to study gas mixtures consisting of 20% methane in an inert carrier gas. Highly condensable argon and practically non-condensable helium were used as carrier gases. It was found that when using the ionized particle selection system for detection, only methane monomers and dimers are registered in mixtures with argon, whereas in mixtures with helium larger clusters are registered. A version of the explanation of the detected dependencies was presented.

Recent progress in reductive carboxylation of C-O bonds with CO2.

Transformation of carbon dioxide (CO2) into value-added organic compounds has attracted increasing interest of scientific community in the last few decades, not only because CO2 is the primary greenhouse gas that drives global climate change and ocean acidification, but also because it has been regarded as a plentiful, nontoxic, nonflammable and renewable one-carbon (C1) feedstock. Among the various CO2-conversion processes, carboxylation reactions represent one of the most beautiful and attractive research topics in the field, since it offers the possibility for the construction of synthetically and biologically important carboxylic acids from various easily accessible (pseudo)halides, organosilicon, and organoboron compounds. The purpose of this review is to summarize the available literature on deoxygenative carboxylation of alcohols and their derivatives utilizing CO2 as a carboxylative reagent. Depending on the C-O compounds employed, the paper is divided into five major sections. The direct dehydroxylative carboxylation of free alcohols is discussed first. This is followed by reductive carboxylation of carboxylates, triflates, and tosylates. In the final section, the only reported example on catalytic carboxylation of fluorosulfates will be covered. Notably, special attention has been paid on the mechanistic aspects of the reactions that may provide new insights into catalyst improvement and development, which currently mainly relies on the use of transition metal catalysts.

Pilot study CCQM-P172 – spectroscopic methods for HNO3 value assignment

Pilot study CCQM-P172 – spectroscopic methods for HNO3 value assignment

CCQM-K68.2019, nitrous oxide (N2O) in air, ambient level, final report

Main textThe key comparison CCQM-K68.2019 was aimed at evaluating the level of comparability of laboratories' capabilities for preparing nitrous oxide in air primary reference mixtures at ambient amount fractions, in the range 320 nmol mol−1 to 350 nmol mol−1.The comparison was coordinated by the BIPM and the KRISS. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories. Two independent analytical methods were used by the BIPM to analyse the amount fraction of N2O in air, namely Gas Chromatography with an Electron Capture Detector (GC−ECD) and Quantum Cascade Laser Absorption Spectroscopy (QCLAS).Since the circulation of the Draft A report in April 2021, four meetings took place with participants to discuss the mathematical treatment of the comparisons results, and several models were proposed. The model chosen by participants is the Bayesian Errors−In−Variables regression with shades of dark uncertainty. In this final report, the Key Comparison Reference Values were obtained with this model, with calculations performed by B Toman and A Possolo.The key comparison CCQM-K68.2019 is considered to present an analytical challenge and therefore classified as Track C comparison in the CCQM nomenclature.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CCQM-P206, nitrous oxide (N2O) in air, ambient level, pilot study run in parallel with CCQM-K68.2019

Main textThe Pilot Study CCQM-P206 was conducted in parallel with the Key Comparison CCQM-K68.2019, which was aimed at evaluating the level of comparability of laboratories' capabilities for nitrous oxide in air primary reference mixtures at ambient amount fractions, in the range 320 nmol mol−1 to 350 nmol mol−1. The Pilot Study was set up to allow the participation of the Scripps Institution of Oceanography of the University of California San Diego (SIO/UCSD) as guest expert laboratory of the CCQM.The SIO/UCSD was invited by the CCQM in view of its long experience in accurate measurements of nitrous oxide in the atmosphere and is the calibration laboratory for this compound in the AGAGE (Advanced Global Atmospheric Gases Experiment) global measurement network. The laboratory has developed a unique method which provides an independent assessment of the N2O amount fraction compared to participants in CCQM-K68.2019. Its participation was also seen as the occasion to contribute to a more general reflexion on the compared advantages of two different systems to ensure traceability: a unique scale maintained by one central laboratory, or the dissemination of materials all traceable to the SI by multiple national metrology institutes.The comparison CCQM-K68.2019 was coordinated by the BIPM and the KRISS. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories. Two independent analytical methods were used by the BIPM to analyse the amount fraction of N2O in air, namely Gas Chromatography with an Electron Capture Detector (GC−ECD) and Quantum Cascade Laser Absorption Spectroscopy (QCLAS).For the Pilot Study, SIO/UCSD provided results of measurements of the N2O amount fraction in the two standards submitted by the Global Monitoring Laboratory of the National Oceanic and Atmospheric Administration (NOAA), a participant in the Key Comparison. Therefore, this study consists in looking at the agreement between SIO/UCSD measurement results and the Key Comparison reference value.All details on the Key Comparison CCQM-K68.2019, including its protocol and its results, can be found in its report. This report focuses on SIO/UCSD results and agreement with participants in the Key Comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Techno-economic assessment of hydrotreated vegetable oil as a renewable fuel from waste sludge palm oil

To date, the development of renewable fuels has become a normal phenomenon to solve the problem of diesel fuel emissions and the scarcity of fossil fuels. Biodiesel production has some limitations, such as two-step processes requiring high free fatty acids (FFAs), oil feedstocks and gum formation. Hydrotreated vegetable oil (HVO) is a newly developed international renewable diesel that uses renewable feedstocks via the hydrotreatment process. Unlike FAME, FFAs percentage doesn't affect the HVO production and sustains a higher yield. The improved characteristics of HVO, such as a higher cetane value, better cold flow properties, lower emissions and excellent oxidation stability for storage, stand out from FAME biodiesel. Moreover, HVO is a hydrocarbon without oxygen content, but FAME is an ester with 11% oxygen content which makes it differ in oxidation stability. Waste sludge palm oil (SPO), an abundant non-edible industrial waste, was reused and selected as the feedstock for HVO production. Techno-economical and energy analyses were conducted for HVO production using Aspen HYSYS with a plant capacity of 25,000 kg/h. Alternatively, hydrogen has been recycled to reduce the hydrogen feed. With a capital investment of RM 65.86 million and an annual production cost of RM 332.56 million, the base case of the SPO-HVO production process was more desirable after consideration of all economic indicators and HVO purity. The base case of SPO-HVO production could achieve a return on investment (ROI) of 89.03% with a payback period (PBP) of 1.68 years. The SPO-HVO production in this study has observed a reduction in the primary greenhouse gas, carbon dioxide (CO2) emission by up to 90% and the total annual production cost by nearly RM 450 million. Therefore, SPO-HVO production is a potential and alternative process to produce biobased diesel fuels with waste oil.