Sulfur Emissions Research Articles

Marine Fuel Regulations and Engine Emissions: Impacts on Physicochemical Properties, Cloud Activity and Emission Factors

AbstractMarine regulations aim to reduce sulfur and nitrogen exhaust emissions from maritime shipping. Here, two compliance pathways for reducing sulfur dioxide emissions, fuel sulfur content reduction and exhaust wet scrubbing, are studied for their effects on physicochemical properties and cloud forming abilities of engine exhaust particles. A test‐bed diesel engine was utilized to study fresh exhaust emissions from combustion of non‐compliant, high sulfur content fuel with (WS) and without (HiS) the usage of a wet scrubber as well as a regulatory compliant, low sulfur content fuel (LoS). Particle number emissions are decreased by ≈99% when switching to LoS due to absence of 20–30 nm sulfate rich particles. While number emissions for WS are also decreased, a shift in the sulfate mode toward larger sizes was found to increase particle mass emission factors by at least 31%. Changes in the mixing state induced by the compliance measures are reflected in the hygroscopicity of the exhaust particles. Fuel sulfur reduction decreased cloud condensation nuclei emissions by at least 97% due to emissions of primarily hydrophobic soot particles. Wet scrubbing increased those emissions, mainly driven by changes in particle size distributions. Our results indicate that both compliance alternatives have no obvious impact on the ice forming abilities of 200 nm exhaust particles. These detailed results are relevant for atmospheric processes and might be useful input parameters for cloud‐resolving models to investigate ship aerosol‐cloud interactions and to quantify the impact of shipping on radiative budgets from local to global scales.

Neutralization of Anthropogenic Acidic Particles by NH3 From Wildfire Over Tropical Peatland

AbstractAcidity is an essential characteristic of aerosol particles that influences chemical and physical properties. Aerosol particles in tropical Asia, such as Singapore, have been reported as highly acidic due to intense anthropogenic sulfur emissions. At the same time, the region has also been experiencing wildfire over tropical peatlands, which is recognized as an intense source of NH3. Here, we investigated the role of NH3 from wildfire on aerosol particles in Singapore by employing the aerosol mass spectrometric technique. The observation was conducted both during wildfire haze (2015 October and 2019 September–October) and non‐haze (2018 October and 2019 April) periods. The observation result demonstrated that inorganic ionic species in Singapore were neutralized by NH4+ during the haze periods. Namely, the degree of neutralization of aerosol particles (i.e., measured NH4+ concentration/predicted NH4+ concentration by assuming that NH4+ fully neutralized SO42−, NO3−, and Cl−) was lower than 0.77during the non‐haze periods. On the other hand, the corresponding values were higher than 0.93 during the haze periods. In addition, NO3− concentration during the daytime of the haze period in 2015 was higher than that in other observation periods. A thermodynamic model calculation suggested that the regime shifts from the “NH3 sensitive region” to the “NH3 and HNO3 sensitive region” or “HNO3 sensitive region” might have occurred during the haze period. In the future, continuous monitoring of both gas‐ and particle‐phase inorganic chemical species will need to be conducted to investigate the impact of wildfire haze on atmospheric chemical processes in more detail.

Research on the impact and intermediary effect of carbon emission trading policy on carbon emission efficiency in China

In this paper, the impact of the carbon emission trading policy on carbon emission efficiency is discussed based on the local data of China from 2004 to 2019, based on the natural experiment of carbon emission trading policy. The intermediary model is introduced to analyze the mediating effect of industrial structure and energy consumption structure in emission reduction. The results show that the carbon emission trading policy not only directly improves the carbon emission efficiency, but also indirectly improves the carbon emission efficiency by upgrading the industrial structure and adjusting the energy consumption structure. Finally, this paper verifies that carbon trading policy has a synergistic emission reduction effect on sulfur emission efficiency. The mechanism of the SO2 reduction is similar to that of the CO2 reduction mechanism, with direct and intermediary effects.

H2 generation from H2S decomposition on Al

Direct decomposition of H2S not only generates H2 but also reduces sulfur (S) emission. Proper catalysts and/or reactant materials are needed to catalyze its dissociation and accommodate the decomposed S in an economical way. Here, by using the density functional theory (DFT) based calculations, we show that Aluminum (Al) can facilitate the dehydrogenation of H2S and the formation of H2. The remaining S adatoms continue to accumulate on Al surface to reach high S coverage (>0.6 monolayer, ML). Then, S atoms react with surface Al atoms to afford a layer of amorphous Al2S3 (a cathode material for Al–S battery) at relatively low temperature (e.g. 773 K), which will transform into crystal phase at higher temperature (e.g. 1073 K). Our research presents a new way to produce H2 and Al2S3 from H2S and Al.

Perishables Liner Bunkering Strategy and Route Optimization Considering Carbon Tax and Sulfur Emissions

For the issue of perishable goods liner shipping route selection and bunkering strategy, this paper gives full consideration to the characteristics of perishable goods, in the context of the carbon tax and the setting of emission control zones, constructs a mixed-integer nonlinear planning model with the goal of minimizing the total weekly cost of liner service, designs a segmented linear approximation algorithm for model solution, and conducts an arithmetic analysis based on the actual liner voyage as an example, which provides a reference for the actual operation of shipping.

Anticipated sulfur dioxide emissions from coal-fired power plants

Southeastern Europe (SEE), which includes Serbia, along with Germany and Poland, is one of the largest producers of solid fuels in Europe. Despite growing environmental concerns, coal, especially lignite, persists and remains the dominant fuel for electricity generation in this region. Concurrently, these power plants emerge as the predominant emitters of pollutants in all the observed states. To conduct a comprehensive analysis, data on major emitters within the European Union were gathered, allowing for a detailed comparison with SEE countries. A specific focus was placed on the thermal power plant Kostolac in Serbia, where the calculation of SO2 emissions for two thermoblocks was undertaken. Comparisons were drawn with emitters in EU countries, with a particular emphasis on SEE nations. The analysis involved data from wells that have undergone excavation over specific periods, facilitating an exploration of the correlation between calculated values, those from exploited wells, and projections of future SO2 emissions from new wells in areas earmarked for surface mining exploitation.

Self-assembly of Dawson-type H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 for high-performance aerobic oxidation desulfurization of fuel.

Because global sulfur emission has escalated, the development of high-efficiency deep desulfurization techniques has become imperative. Herein, to design a high-activity heterogeneous catalyst for the aerobic oxidation desulfurization (AODS) of fuel, Dawson-type polyoxometalate (H6P2W18O62 abbreviated as D-P2W18), characterized by its high activity and strong oxidative capacity, was applied to react with CuCl2·2H2O and H3TZI via a one-pot hydrothermal method. Consequently, blue crystalline H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 (abbreviated as D-P2W18@rht-MOF-1; rht-MOF-1 = [Cu6O(TZI)3(H2O)6]4·nH2O) was afforded. X-ray diffraction analysis indicated that D-P2W18 was successfully encapsulated in two different cages of rht-MOF-1, which is distinct from the crystal structure of Keggin-type POMs@rht-MOF-1. It represents the first crystal structure of Dawson-type POMs@rht-MOF-1. When D-P2W18@rht-MOF-1 was employed as a catalyst for AODS under ambient oxygen pressure with the assistance of surfactant dioctadecyl dimethyl ammonium chloride (DODMAC), it demonstrated remarkable catalytic capability and recyclability for both model fuel and commercial diesel. Further, the AODS reaction mechanism, identified as a free radical oxidation-reduction process, was verified by way of radical quenching experiments, EPR and XPS analysis. This approach offers a feasible route for the synthesis of new Dawson-type POMs@MOFs of heterogeneous catalysts for highly active AODS of fuel.

Atmospheric deposition and soil water chemistry in Swedish forests since 1985 – Effects of reduced emissions of sulphur and nitrogen

Trends for the atmospheric deposition of sulphur (S) and inorganic nitrogen (inorg-N) to forests and changes in the forest soil water chemistry in Sweden have been assessed since 1985, with special focus on the last 25 years, based on measurements within the Swedish Throughfall Monitoring Network (SWETHRO). The reductions in the deposition of S and inorg-N in the southern part of Sweden corresponded relatively well with the pollutant emission reductions for S and inorg-N from both EU27 + UK and Sweden during 1996/97–2021/22. For northern Sweden the deposition of S and inorg-N decreased to a lesser extent than both European and Swedish emissions. The bulk deposition of NO3-N has decreased more than the deposition of NH4-N over the last 25-year period, which is consistent with the much larger emission reductions for NOx compared to NH3 from EU27 + UK and Sweden. The S concentrations in the soil water, at 50 cm below soil surface, have decreased during the last 25 years, however somewhat less than the S deposition. At sites with low ANC and pH in the beginning of the period, the increase in ANC was generally greater and the increase in pH was smaller, but at sites with high pH and ANC above zero, the increase in pH was dominant, in line with the nonlinear relationship between pH and ANC in the soil water. The incidence of elevated concentrations of NO3-N in the soil water was highest in southwest Sweden, ranging between 4 and 19 % of all measuring occasions since 1985/86. The reduced deposition of N over the 35-year period was not reflected in the incidence of elevated concentrations of NO3-N in the soil water over time.

Torrefaction of Willow in Batch Reactor and Co-Firing of Torrefied Willow with Coal

The torrefaction process represents a thermal conversion technique conducted at relatively low temperatures ranging between 200 to 300 °C. Its objective is to produce fuel with a higher energy density by decomposing the reactive portion of hemicellulose. In this study, the kinetics of mass loss during torrefaction were investigated for willow. The experiments were carried out under isothermal conditions using thermogravimetric analysis. Batch torrefaction reactor designs were conducted and explained in detail. Co-combustion of willow with hard coal (origin: Katowice mine) in different mass ratios (25% biomass + 75% coal, 50% biomass + 50% coal, and 75% biomass + 25% coal) was conducted in addition to raw biomass torrefaction. TG/MS analysis (a combination of thermogravimetric analysis with mass spectrometry analysis) was performed in the research. The optimal torrefaction conditions for willow were identified as an average temperature of 245 °C and a residence time of 14 min, resulting in the lowest mass loss (30.15%). However, it was noted that the composition of torgas, a by-product of torrefaction, presents challenges in providing a combustible gas with sufficient heat flux to meet the energy needs of the process. Prolonged residence times over 15 min and higher average temperatures above 250 °C lead to excessive energy losses from volatile torrefaction products, making them suboptimal for willow. On the other hand, the co-combustion of torrefied biomass with hard coal offers advantages in reduced sulfur emissions but can lead to increased NOx emissions when biomass with a higher nitrogen content is co-combusted in proportions exceeding 50% biomass. This paper summarizes findings related to optimizing torrefaction conditions, challenges in torgas composition, and the emissions implications of co-combustion.

A coordinated generation and voyage planning optimization scheme for all-electric ships under emission policy

The International Maritime Organization has introduced the concept of Emission Control Area to reduce sulfur emissions from coastal areas. The expensive low-sulfur fuels are required to be used in Emission Control Area, leading to increased sulfide emissions due to bypassing by ship operators. It creates new challenges for navigation and power generation scheduling of all-electric ships. This article presents a new bi-objective joint optimization scheme for ship sailing routes and energy management. It considers emission control strategies to balance the total cost of operation and sulfur dioxide emissions throughout the ship’s voyage. Unlike previous optimization problems with fixed routes and sailing time, the influence of emission policies on the operator’s navigation decisions is considered. The route options and sailing time are treated as variables embedded in the model. In addition, the optimization accuracy is improved by integrating the model into mixed integer linear programming through a modified piecewise linearization model. The results show that the total operating cost for the same route is reduced by 6.05%, and the SO2 emission is 8.36% after integrating the emission policy influencing factor in the model. The effectiveness of the proposed scheme is validated, and the model’s necessity for optimizing ship power generation and voyage within Emission Control Area is also illustrated.

Performance assessment of state-of-the-art and novel methods for remote compliance monitoring of sulfur emissions from shipping

Abstract. The fuel sulfur content (FSC) of ocean-going and inland vessels was measured simultaneously by eight different state-of-the-art and novel monitoring systems during a 6-week campaign at the Elbe River, at a distance of about 10 km to the port of Hamburg, Germany. Both stationary and airborne systems on unoccupied aerial vehicles (UAVs) were operated by four participating partners in a side-by-side measurement setup to measure the emission factors of the same emission sources. A novel laser spectrometer, with significantly better-precision specifications as compared with the other instruments, was used for the first time for emission monitoring regarding the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex VI regulations. The comparison took place in the North Sea sulfur emission control area (SECA), where the allowed FSC is limited to 0.10 %Sm/m. The unit %Sm/m relates to the percentage of mass sulfur per mass combusted fuel. In total, 966 plumes that originated from 436 different vessels were analysed in this study. At the same time, fuel samples obtained from 34 different vessels and bunker delivery notes (BDNs) from five frequently monitored vessels were used as a reference to assess the uncertainties of the different systems. Seven of the eight measurement systems tended to underestimate the FSC found from fuel samples and BDNs. A possible relation between underestimation and high relative humidities (above 80 %) was observed. The lowest systematic deviations were observed for the airborne systems and the novel laser spectrometer. The two UAV-borne systems showed total uncertainties of 0.07 %Sm/m and 0.09 %Sm/m (confidence level: 95 %). The novel laser spectrometer showed the lowest total uncertainty of 0.05 %Sm/m compared with other stationary sniffer systems, whose total uncertainties range from 0.08 %Sm/m to 0.09 %Sm/m. It was concluded that non-compliant vessels, with an actual FSC of the combusted fuel above 0.15 %Sm/m to 0.19 %Sm/m, can be detected by the compared systems with 95 % confidence.

Optimal Shipping Route under the Designation of the Mediterranean Sulfur Emission Control Area: Mathematical Models and Applications

In order to tackle sulfur oxides (SOx) emissions from maritime activities, both local governmental bodies and the International Maritime Organization (IMO) have implemented a range of regulations with the establishment of sulfur emission control areas (SECAs) being one crucial measure. Recently, the IMO made the significant decision to designate the Mediterranean as an SECA, aiming to promote environmental conservation as well as sustainable development in the maritime industry and mitigate the adverse health effects caused by air pollutants emitted from ships in Mediterranean regions. While this policy signifies significant progress in the reduction of sulfur emissions, it simultaneously presents intricate challenges for maritime enterprises. Notably, under the Mediterranean SECA designation, shipping companies may opt to bypass this region and choose routes through the Cape of Good Hope as a means of minimizing the overall costs, resulting in a potential increase in global carbon emissions. To support shipping companies in formulating optimal strategies within the framework of this new policy, the research introduces advanced techniques to make the optimal decisions concerning route selection, sailing speeds, and the appropriate number of ships for both SECAs and non-SECAs. Furthermore, we elucidate how these optimal decisions can be dynamically adapted in response to the dynamic fluctuations in fuel prices and the weekly operational expenditures incurred by maritime fleets. In the experimental results, taking into account factors like route distance and fuel costs, shipping companies select routes through the Mediterranean region in both eastward and westward directions. The total cost amounts to $6,558,766.78, utilizing eight vessels. Regarding ship speeds, vessels sail at reduced speeds in SECAs compared to non-SECAs. Furthermore, longer voyage distances require deploying a greater number of ships to maintain a weekly service frequency. This research exhibits robust timeliness and practicality, which is in line with practice. It not only timely supplements and enhances the extant body of knowledge concerning SECAs but also serves as a valuable point of reference and emulation for shipping companies seeking to optimize their operations within the framework of the new policy landscape. Furthermore, it offers pertinent insights for the IMO in formulating policies related to SECAs.

Geochemical and Photochemical Constraints on S[IV] Concentrations in Natural Waters on Prebiotic Earth

AbstractAqueous S[IV] species (, ) derived from volcanogenic atmospheric SO2 are important to planetary habitability through their roles in proposed origins‐of‐life chemistry and influence on atmospheric sulfur haze formation, but the early cycling of S[IV] is poorly understood. Here, we combine new laboratory constraints on S[IV] disproportionation kinetics with a novel aqueous photochemistry model to estimate the concentrations of S[IV] in natural waters on prebiotic Earth. We show that S[IV] disproportionation is slow in pH ≥ 7 waters, with timescale T ≥ 1 year at room temperature, meaning that S[IV] was present in prebiotic natural waters. However, we also show that photolysis of S[IV] by UV light on prebiotic Earth limited [S[IV]] < 100 µM in global‐mean steady‐state. Because of photolysis, [S[IV]] was much lower in natural waters compared to the concentrations generally invoked in laboratory simulations of origins‐of‐life chemistry (≥10 mM), meaning further work is needed to confirm whether laboratory S[IV]‐dependent prebiotic chemistries could have functioned in nature. [S[IV]] ≥ 1 µM in terrestrial waters for: (a) SO2 outgassing ≥20× modern, (b) pond depths <10 cm, or (c) UV‐attenuating agents present in early waters or the prebiotic atmosphere. Marine S[IV] was sub‐saturated with respect to atmospheric SO2, meaning that atmospheric SO2 deposition was efficient and that, within the constraints of present knowledge, UV‐attenuating sulfur hazes could only have persisted on prebiotic Earth if sulfur emission rates were very high (≳100× modern). Our work illustrates the synergy between planetary science, geochemistry and synthetic organic chemistry toward understanding the emergence and maintenance of life on early Earth.

Response of distributions and emissions of summer biogenic sulfur in the Pacific Arctic to enhanced Pacific Water inflow

AbstractThe inflow of warm and nutrient‐rich Pacific Water (PW) through the Bering Strait into the Arctic Ocean is likely to have far‐reaching consequences for the ecosystem and biogenic sulfur cycle in the Earth's sensitive subarctic–arctic region of the Pacific sector, even impacting climate change under global warming scenarios. We performed a detailed biogeochemical study of summer biogenic sulfur cycling from cold (2012) to warm (2014) years in the Bering Strait and the Chukchi Sea, so as to highlight the importance of enhanced Pacific inflow in driving dimethylsulfide (DMS) variability. In the Bering Strait, the enhanced Pacific inflow led to the vertical expansion of the eastern high‐DMS regions due to the vertical extension of Alaska Coastal Water, and the horizontal expansion of the western surface high‐DMS regions due to the westward intrusion of Bering Shelf Water. The enhanced extension of PW potentially stimulated seawater warming, the northward retreat of the ice edge, and the enlargement of sea ice‐free areas in the Chukchi Sea. The northern ice melting zone at 71°N with a bloom of phytoplankton was an area of locally high dimethylsulfoniopropionate concentrations and slow DMS consumption in 2012. A hotspot for dimethylated sulfur compound concentrations and DMS sea–air flux occurred in the convergence region near 67.7°N during 2014, due to enhanced mixing caused by increased Bering Sea Water. Owing to the increased advection of PW during 2012–2014, surface DMS and its emission to the atmosphere increased sharply by threefold in the Chukchi Sea.

Environmental regulation and green transition: Quasi-natural experiment from China's efforts in sulfur dioxide emissions control

Exploiting the target-based pollutant emissions abatement policy imposed on the Two Control Zones in the post-2000 period as an exogenous shock to the strengthening of environmental regulation, we empirically investigate its causal effect on the green transformation of Chinese manufacturing enterprises with the difference-in-differences identification strategy. The empirical results show that the target-based pollutant emissions abatement policy for the Two Control Zones in the post-2000 period effectively binds regulated enterprises’ sulfur dioxide emissions behavior and lowers their sulfur dioxide emissions intensity, indicating that strict environmental regulation contributes to the green transition of enterprises. To avoid the self-selection bias, we re-evaluate the green transition effect of the target-based pollutant emissions abatement policy by employing the propensity score matching with the difference-in-differences technique. Our finding that strict environmental regulation facilitates the green transition of enterprises still holds. Our heterogeneity analyses reveal that enterprises exposed to greater environmental regulation intensity experience a larger reduction in their pollution emissions intensity. State-owned enterprises and those with higher production efficiency are more inclined to achieve green transition under environmental protection pressure. Further mechanism checks confirm that enterprises reduce pollution emissions intensity by upgrading pro-environmental technology rather than increasing expenditure on pollution abatement facilities.

In situ biomass burning enhanced the contribution of biogenic sources to sulfate aerosol in subtropical cities

Sulfurous gases released by biogenic sources play a key role in the global sulfur cycle. However, the contribution of biogenic sources to sulfate aerosol in the urban atmosphere has received little attention. Emission sources and formation process of sulfate in Guangzhou, a subtropical mega-city in China, were clarified using multiple methods, including isotope tracers and chemical markers. The δ18O of sulfate suggested that secondary sulfate was the dominant component (84 %) of sulfate aerosol, which mainly formed by transition metal ion (TMI) catalyzed oxidation (31 %) and OH radical oxidation (30 %). The factors driving secondary sulfate formation were revealed using a tree boosting model, which suggested that NH3, temperature, and oxidants were the most important factors. The δ34S of sulfate indicated that biogenic sources accounted for annual average of 26.0 % of the sulfate, which increased to 30.4 % in winter monsoon period. Rice straw burning enhanced sulfate formation by promoting the release of reduced sulfur from soil, which is rapidly converted into sulfate under a subtropical urban atmosphere with high concentration of NH3 and oxidants. This study revealed the important influence of rice straw burning on biogenic sulfur emission during the rice harvest, thereby providing insight into the sulfur cycle and regional air pollution.

Externalities Analysis on Heat Pump System (EU)

This paper analysis the positive externalities of using heat pumps in European so-ciety to solve the high-temperature problem. Through the paper, heat pump as a potential solution to the climate problem, contemplating how it is done, why it is the best solution, and what are the positive externalities specifically to the City of London. The heat pump is renewable and can reduce carbon dioxide and sulfur emissions. In order to better introduce the benefits of heat pumps in those high-temperature cities, the author thus chooses to create a hypothetical city which is called M&M City. In the stimulating process, we predict the specific circum-stances of heat pumps that may be needed in the simulated city and associated packages, analyze the value and feasibility, as well as present the shortcomings and look to the future.

VogCast: A Framework for Modeling Volcanic Air Pollution and Its Application to the 2022 Eruption of Mauna Loa Volcano, Hawai'i

AbstractVolcanic activity and the associated gas emissions into the atmosphere often result in adverse air quality conditions and present a hazard to human health and the environment. Building on a decade‐long effort to provide operational surface sulfur dioxide and sulfate aerosol forecasts for the State of Hawai'i, we present an air quality modeling framework called VogCast. VogCast is designed to simplify ensemble air quality prediction on a regional scale by linking together multiple state‐of‐the‐art models of meteorology, emissions, and dispersion. The framework is open‐source and introduces a new dynamic plume‐rise algorithm for distributing pollutants vertically. Using radar and satellite data, we demonstrate that VogCast reasonably captured the mean injection height, the location, and the general envelope of the vog plume during Mauna Loa's 2022 eruption. The results suggest that during the 12‐day eruption period model performance varied between days with trade and non‐trade wind conditions. Our findings also highlight the importance of sulfur dioxide emission rate and vent parameter inputs for improving forecast accuracy. The broad goal of this work is to better our understanding of vog dispersion and improve air quality prediction for impacted communities.

Integrated production of potash fertilizer and formed coke via carbonated consolidation technique

Transforming potassium feldspar (PF) into water-soluble potassium fertilizer traditionally requires high-temperature conditions, a significant challenge in sustainable agriculture. Addressing this, our study innovatively employed the carbonated consolidation process using low-rank semi-coke (SC). By introducing PF and alkaline earth metal salts, we produced high-strength formed coke (FC). Crucially, the combustion heat from FC facilitated the desired transformation in the coke ash. Our findings highlight that FC with PF addition yields a calorific value of 20.8 MJ/Kg, aligning with industrial standards, and significantly curtails emissions of sulfur, nitrogen compounds, and dust, emphasizing its eco-friendly nature. Remarkably, a 96.5% potassium leaching rate was achieved within 4 h at 25 °C. Further analyses showcased the FC's carbonate content's role in drastically reducing the transformation temperature of potassium in PF to a mere 570 °C. This research not only offers a cleaner approach to SC utilization but also paves the way for cost-effective and eco-friendly PF transformations, bearing significant implications for future sustainable agricultural practices.

Diesel Hydrodesulfurization and its Impact on the Fuel Market in Ecuador: A Review

This article examines the hydrodesulfurization process used to produce diesel with low sulfur content in Ecuador. The analysis covers the level of processing in the country, the quality of domestic diesel compared to other nations, and the technical and economic requirements of the process. It also explores the need to modify or upgrade catalysts to achieve deep hydrodesulfurization.. Unfortunately, the review found that sulfur content in Ecuadorian deposits is very high, with 3.53 MMkg produced in 2018. Despite improvements in the country’s refineries, diesel sulfur content has only been reduced to 110 ppm.. Ecuador regulates sulfur emissions through the Ecuadorian standard NTE INEN-1489 (2012). This norm classifies the fuel into three types, diesel #1 (3000 ppm), diesel #2 (7000 ppm), and premium diesel (500 ppm), following the use of diesel both in the industrial and transportation sectors. However, Ecuador seeks to adjust to countries with stricter regulations, such as the European Union. The standard that regulates sulfur emissions in this community is Euro VI, which limits the concentration to 10 ppm. One of the challenges in achieving international standards in the hydrodesulfurization units of the Ecuadorian refineries is to modify or improve the catalytic systems. Trimetallic catalysts, both supported and unsupported, can help overcome this challenge by decomposing the refractory molecules (e.g., dibenzothiophene and 4,6-dimethyldibenzothiophene) found in deep hydrodesulfurization. These catalysts can handle molecules that commonly used catalysts such as CoMo or MoW cannot. Therefore, proposals such as using trimetallic catalysts to achieve deep hydrodesulfurization levels are techno-economic options for Ecuador.
 Keywords: diesel, sulfur, Ecuador, hydrodesulfurization, refineries, catalyst.