Translation. Region: Russian Federal
Source: Novosibirsk State University – Novosibirsk State University –
The NSU-NNC Accelerator Mass Spectrometry Shared Use Center conducted the first analysis of biocarbon content in sustainable aviation fuel (SAF) samples. Four samples of different origin were analyzed during the laboratory study. The results showed that the accelerator mass spectrometry method can become a routine method for analyzing biocarbon in SAF aviation fuel.
— We were approached by specialists from the Gubkin Russian State University of Oil and Gas (Moscow) to analyze the biocarbon content in kerosene samples using accelerator mass spectrometry. This analysis is necessary for the certification of the aviation fuel they are developing and its further use within the framework of modern requirements. This development is of particular relevance, which will only increase over time: in order to reduce the carbon footprint, the International Civil Aviation Organization (ICAO) launched the CORSIA program in 2016, which obliges airlines to compensate for the growth of emissions. The goal of this program is to prevent the growth of carbon dioxide emissions relative to the 2020 level. Russia also plans to participate in this international program. From 2025, flights from the EU must use 2% SAF (Sustainable Aviation Fuel) — fuel with a biogenic component. By 2050, this share will reach 63%, — said Ekaterina Parkhomchuk, Director of the NSU-NNC UMS Collective Use Center.
SAF (Sustainable Aviation Fuel) is a product of processing biomass, which includes vegetable oils, animal fat, lignocellulosic wood waste, and microalgae. Processing, depending on the type of feedstock, may include catalytic hydrogenation, hydrocracking, hydrodeoxygenation, isomerization, gasification, and the Fischer-Tropsch process. The resulting processing product is then added to kerosene obtained from fossil hydrocarbon sources.
Russia is one of the largest producers of jet fuel — 12.8 million tons of this type of fuel were produced in 2021 — and also has huge raw material potential for SAF production. In 2020, the production of vegetable oils amounted to 7.3 million tons. The production of “sustainable aviation fuel” requires certification and control over compliance with the requirements for the minimum content of the “biocarbon” share, so a routine method for its analysis is needed. This analysis can be performed by measuring the concentration of radiocarbon, for example, indirectly by the radioactivity of the material, or by the direct method of accelerator mass spectrometry (AMS). Both methods for determining radiocarbon have been developed in Russia, but accelerator mass spectrometry is represented only in the Novosibirsk UMS Center of Collective Use of NSU-NNC.
Search for biogenic carbon
— “Biogenic” carbon differs from fossil carbon in its isotopic composition — primarily in the concentration of the radioactive isotope C-14 (radiocarbon) relative to the main stable isotope C-12. In modern biological objects, the proportion of radiocarbon, although extremely small — about 10 to the minus tenth power % — is still at a level detectable by modern technology; however, due to the beta decay of the C-14 nucleus, over time the amount of radiocarbon in fossil raw materials becomes orders of magnitude smaller and quantitative determination becomes impossible.
Accelerator mass spectrometry provides the ability to reliably measure the concentration of radiocarbon in any samples at a level above 10 to the -14th power %, which is 0.01% of the current level in the biosphere. Therefore, by conducting UMS analysis of any materials, including kerosene, food additives, drugs, etc., it is possible to determine with high accuracy the proportion of carbon of modern biological origin, – explained Ekaterina Parkhomchuk.
The NSU-NNC UMS Collective Use Center received 4 samples from RGUNG as introductory or test experiments, including two reference (standard) samples, which were kerosene obtained exclusively from biological raw materials and kerosene from fossil oil, as well as two samples of kerosene obtained by mixing the first two in proportions unknown to Novosibirsk scientists. Innovative sample preparation aimed at overcoming the “sulfur barrier” was used in the analysis of the samples. As Ekaterina Parkhomchuk explained, the complexity of fuel analysis lies in the high content of sulfur and nitrogen, which cause rapid corrosion of measuring instruments. A unique graphitizer has been developed at Novosibirsk State University, which allows working even with high-sulfur oils. This gives Russia a technological advantage over foreign analogues.
— UMS analysis requires the production of a graphite cathode from the material being studied. This is done by burning the sample, extracting the target carbon dioxide from the resulting complex gas mixture and catalytically carbonizing it into elemental graphite. The difficulty of analyzing most hydrocarbon fuels is that the material may contain impurity elements such as sulfur and nitrogen, which quickly disable traditionally used “graphitizers”, such as those offered by the Swiss company Ionplus. Several years ago, NSU developed and assembled a graphitization stand that allows for the preparation of graphitized samples for UMS cathodes with sufficient purity even from high-sulfur oils, which distinguishes it from foreign analogues. It was used for the work described, — said Ekaterina Parkhomchuk.
The studies were conducted under special conditions, observing all standardized requirements for laboratories that conduct radiocarbon studies not only of ancient samples, but also of samples containing excessive amounts of radiocarbon. These measures are designed to ensure radiation and biological safety, as well as to prevent cross-contamination of samples and false test results. Sample preparation of biological and C-14-labeled samples is carried out in different laboratories. Personnel working in one laboratory do not have access to the other. Employees of both laboratories maintain isolation from each other, do not cross paths in offices, lunch rooms, and recreation areas. Also, both laboratories use separate chemicals, materials, and utensils.
— Three graphite cathodes were made from each sample and UMS analysis was performed on all samples. It turned out that one reference sample did not contain C-14, i.e. it belonged to fossil raw materials (most likely oil), and the concentration of radiocarbon in the second reference sample slightly exceeded the modern level of C-14. This indicates that the time of origin of the plant raw materials from which the biogenic fuel was obtained corresponds to the period 2000-2010, when the concentration of radiocarbon in the atmosphere was still higher than usual as a result of nuclear tests conducted in the 50-70s of the last century. In other words, both samples really belonged to two different sources of production — fossil (oil, gas or coal) and modern (biomass). And the other two samples showed results different from the first two — one contained about 6% biogenic carbon, and the second — about 13%. Our experimental results coincided with the calculated ratios, according to which the RGUNG specialists prepared mixed samples, which confirms the validity of using the UMS method to determine biocarbon, – summed up Ekaterina Parkhomchuk.
Promising technology
The technology of joint processing of lignocellulosic raw materials PCH-SAF, developed at the Gubkin Russian State University of Oil and Gas (National Research University), is based on the processes of fast pyrolysis, delayed coking and hydrocracking of traditional oil and plant raw materials. Waste is used as the initial biomass – sawdust of coniferous and deciduous trees, sunflower husks, etc.
— This technology consists of the joint processing of plant and oil raw materials. There are three stages of obtaining the component: fast pyrolysis of biomass, coking and hydrocracking. By means of fast pyrolysis, we liquefy the initial biomass and obtain the so-called bio-oil at the output. At the coking stage, co-processing of oil residues, for example, tar, with bio-oil occurs. At the hydrocracking stage, the raw material is a mixture of vacuum gas oil with the gas oil fraction of the coking process, containing bio-oil components, — explained Mikhail Ershov, professor of the Department of Oil Refining Technology.
One of the advantages of the technology developed at RGUNG is the use of the existing infrastructure of oil refineries. It is assumed that when it is implemented on an industrial scale, there will be no need to replace the catalyst at the hydrocracking unit, and if necessary, only the process conditions may need to be adjusted. The process is currently at the laboratory stage, a laboratory sample has been developed and is being tested. This work is being carried out within the framework of the RSF grant No. 22-79-10280 “Study of new methods for obtaining renewable aviation fuel from lignocellulosic biomass using a complex of thermal and thermocatalytic processes.”
Prospects for cooperation
Mikhail Ershov clarified that kerosene obtained using PCH-SAF technology must meet the requirements of GOST 10227, which applies to fuels for jet engines, and be no different from petroleum kerosene.
— In the context of the global transition to renewable energy sources, green fuel and reducing the carbon footprint, we must follow these trends. Compliance with ICAO emissions requirements will contribute to the growth of imports of renewable components, and therefore dependence on supplier countries (China, India). The PCH-SAF technology we propose, due to the existing infrastructure, will allow for a short transition to the production of aviation biofuel with a reduced carbon footprint without significant capital investments. In case of successful testing and confirmation of a reduction in the carbon footprint, it is necessary to approve such fuel with the participation of leading organizations FAU “25th State Research Institute of Chemmotology of the Ministry of Defense of the Russian Federation”, FAU “TsIAM named after P.I. Baranov”, FSUE GosNII GA for use in civil and military aircraft, — he said.
Mikhail Ershov noted that currently there is no domestic method for measuring biogenic components in petroleum products, in particular, aviation fuel. However, with an increase in the share of biogenic raw materials involved, there will be a need to confirm the biogenicity of fuels. Therefore, RGUNG specialists plan to develop a standard method for determining biocarbon using UMS together with NSU scientists.
Ekaterina Parkhomchuk believes that the UMS method has proven its accuracy, sensitivity and reliability, and can become a key tool for the transition of aviation to “green” rails. And the introduction of the technology developed by RGUNG specialists into industry will open the way for Russia to leadership in the production of sustainable aviation fuel.
— Currently, standard methods for analyzing materials for biogenic origin have been developed in different countries, and radiocarbon analysis is considered the “gold standard” among all possible methods. The method of accelerator mass spectrometry, unique in sensitivity, accuracy, and productivity, and the sample preparation methods we have developed are considered very promising for this new area of economic activity, — Ekaterina Parkhomchuk summarized.
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