Caracterização por cromatografia gasosa de óleos vegetais e ceras parafínicas

Mestrado em Métodos Instrumentais e Controlo de Qualidade AnalíticaGrande parte da energia consumida no mundo provém do petróleo, do carvão e do gás natural. A escassez das fontes de energia, especialmente da energia fóssil, devido à impossibilidade de renovação, tem motivado o desenvolvimento de novas tecnologias que permitam utilizar fontes renováveis de energia e menos poluentes. O biodiesel é composto por ésteres metílicos ou etílicos de ácidos gordos, obtido de fontes renováveis através de uma reacção de transesterificação. Este combustível é biodegradável, renovável e tem baixos níveis de emissão de CO2, comparado com os combustíveis convencionais, apresentando características físico-químicas semelhantes às do diesel fóssil. Sendo o sector habitacional, um dos grandes responsáveis, junto com os transportes pelos elevados consumos energéticos, uma forma de minimizar consumos é através da utilização de sistemas de armazenamento de energia ou isolamentos térmicos mais eficientes. Os óleos e gorduras vegetais saturados, tal como as ceras parafínicas, fundem a temperaturas ideais para serem utilizados como armazenadores de energia sob a forma de calor latente. As gorduras vegetais podem assim ser um biomaterial renovável alternativo aos materiais de mudança de fase (PCM) convencionais. Neste trabalho foram caracterizadas por CG-MS várias amostras de óleos e gorduras vegetais transesterificadas, assim como de algumas amostras de biodiesel. As concentrações dos ácidos gordos presentes nos óleos e gorduras vegetais analisadas encontram-se dentro dos intervalos apresentados na literatura. A amostra de óleo de coco foi derivatizada e analisada directamente no GC-MS sem transesterificação, de modo a determinar-se a composição dos triglicerídeos. Algumas das gorduras estudadas foram caracterizados por DSC e verifica-se que as manteigas de cacau, kpangnan, karité e o óleo de coco virgem apresentam uma entalpia de fusão elevada o que permite que possam ser utilizadas como PCM. Foram ainda caracterizadas por GC-MS algumas amostras de ceras parafínicas extraídas de crudes, que também podem ser utilizadas como PCMs. Desenvolveu-se ainda, um método fiável para análise de ceras em GCFID. ABSTRACT: Most of the energy consumed in the world comes from petroleum, charcoal and natural gas. The scarceness of energy sources, especially fossil ones, has been a strong incentive towards the development of new and less pollutant technologies based on renewable energy resources. Biodiesel is constituted by methyl or ethyl esters of fatty acids obtained from renewable resources through a transesterification reaction. This fuel is biodegradable, renewable, results in low CO2 emission levels, (unlike other common fuels) and has similar physical-chemical properties when compared with fossil diesel. Since housing and transportation are among the main energetic consumption sources, the use of some form of energy storage systems or more efficient thermal isolation can be important ways to minimize consumption. Saturated vegetable oils and fats, such as paraffinic waxes, have melting temperatures that render them ideal for latent heat energy storage. Vegetable fats can therefore constitute an alternative renewable biomaterial to common phase change materials (PCM). In the present work, several samples of transesterificated vegetable oils and fats, as well as some biodiesels, were characterized by CG-MS, the concentrations of fatty acids in vegetable oils and fats being in agreement with available literature. Coconut oil was directly analysed in GC-MS without transesterification in order to determine its triglyceride composition. Some of the studied fats were characterized by DSC. It was observed that cocoa, kpangnan, karité butter and virgin coconut oil show high fusion enthalpies, which allows their use as PCM. Some paraffinic waxes extracted from crude were also characterized by GC-MS, indicating possible usage as PCM. Furthermore, a method for the analysis of waxes using the GC-FID was also developed

Size fractionated atmospheric aerosol in the Iberian Peninsula

Doutoramento em Ciências e Engenharia do AmbienteUm dos principais fatores que afetam negativamente a qualidade do ambiente em muitas cidades em todo o mundo é o material particulado (PM). A sua presença na atmosfera pode ter impactos negativos na saúde humana, clima, património edificado e ecossistemas. Muitos dos estudos realizados em áreas urbanas focam apenas as frações respiráveis (PM10 e PM2,5). No entanto, os processos de formação, a identificação das fontes emissoras e os efeitos dependem muito da distribuição granulométrica das partículas. A atenção tem recaído na análise de hidrocarbonetos poliaromáticos (PAHs), devida à sua carcinogenicidade e a informação disponível sobre outros compostos é escassa. O presente estudo consistiu na obtenção do PM distribuído por diferentes frações de tamanho e na análise detalhada da sua composição química, em dois locais urbanos da Península Ibérica (Madrid e Lisboa). Dado que os veículos representam uma das principais fontes emissoras em ambientes urbanos, efetuou-se uma caracterização mais detalhada deste tipo de emissões, conduzindo uma campanha de amostragem num túnel rodoviário (Marquês de Pombal, Lisboa). As amostragens, em ambas as cidades, decorreram durante um mês, quer no verão quer no inverno, em dois locais urbanos distintos, um junto a uma via com influência de tráfego e outro numa área urbana de fundo. No túnel a amostragem foi realizada apenas durante uma semana. Em Madrid e no túnel, o PM foi recolhido utilizando um amostrador de elevado volume com impactor em cascata com quatro tamanhos: 10-2,5, 2,5-0,95, 0,95-0,49 e < 0,49 μm. Em Lisboa, foi utilizado um impactor em cascata com apenas dois tamanhos, 10- 2,5 e < 2,5 μm. As amostras foram quimicamente analisadas e determinadas as concentrações de compostos carbonados (OC, EC e carbonatos), iões inorgânicos solúveis em água (Cl−, NO3−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+),metais e compostos orgânicos. Em Madrid, as concentrações médias de PM10 foram 44 e 48% maiores nas amostras recolhidas junto à estrada do que as de fundo urbano no verão e inverno, respetivamente. A fração grosseira e o PM0,5 apresentaram concentrações mais elevadas no verão do que no inverno devido às condições climatéricas pouco usuais. No verão, as amostragens decorreram num mês em que as temperaturas foram muito elevadas e em que ocorreram vários episódios de intrusão de poeira africana. Durante o período de amostragem de inverno, as temperaturas foram muito baixas e registaram-se vários dias de precipitação quer sob a forma de chuva, quer sob a forma de neve. As situações meteorológicas sinóticas mais comuns, incluindo aquelas que causam o transporte de massas de ar com poeiras Africanas, foram identificadas em ambas as estações do ano. As concentrações mássicas de PM10, EC e OC foram encontrados predominantemente na fração de tamanho ultrafino em ambos os locais de amostragem e estações do ano. Nas restantes frações não se observou nenhuma tendência sazonal. O carbono orgânico secundário (SOC) mostrou um claro padrão sazonal, com concentrações muito mais elevadas no verão do que no inverno, em ambos os lugares. A partir do balanço mássico de iões, observou-se que, no verão, a formação de compostos inorgânicos secundários (SIC) conduziu a um enriquecimento pouco comum de Ca2+ na fração submicrométrica, quer nas amostras de tráfego, quer em fundo urbano. Os alcanos, PAHs, os álcoois e os ácidos foram as classes de compostos orgânicos identificados e quantificados no material particulado. Globalmente, representaram 0,26 e 0,11 μg m−3 no verão e inverno, respetivamente, no local de tráfego e 0,28 e 0,035 μg m−3 na área urbana de fundo. Os diferentes compostos orgânicos também apresentaram padrões sazonais, sugerindo fontes de emissão (e.g. escapes dos veículos e fontes biogénicas) ou processos de formação com contribuições variáveis ao longo do ano. As concentrações de benzoapireno equivalente foram menores que 1 ng m-3 e o risco carcinogénico estimado é baixo. No verão, os maiores enriquecimentos de metais ocorreram na fração submicrométrica, e no inverno na fração grosseira. No verão, os enriquecimentos foram ≥ 80% para o Mn, Ni, Cu, Zn, Cd, Sb e Co, no inverno, estes traçadores de emissões do tráfego foram menores, exceto para o Zn. Em Lisboa, a concentração média de PM10 foi de 48 μg m-3 no verão e de 44 μg m-3 no inverno, junto à estrada. Na área de fundo urbano, registaram-se níveis comparáveis nas duas estações (27 μg m-3 e 26 μg m-3). A média do rácio PM2,5/PM10 foi de 65% no verão e 44% no inverno na área de tráfego e 62% e 59% na área urbana de fundo. Estes resultados significam que o PM2,5 é um dos principais contaminantes que afetam a qualidade do ar no centro da cidade de Lisboa. A relação OC/EC, que reflete a composição das emissões de combustão dos veículos, variou entre 0,3 e 0,4 no interior do túnel. Os rácios de OC/EC mínimos obtidos junto às vias de tráfego em Madrid e em Lisboa encontram-se entre os do túnel e os registados em atmosferas urbanas de fundo, sugerindo que os valores mínimos habitualmente obtidos para este parâmetro em ambientes urbanos abertos sobrestimam as emissões diretas de OC pelo transporte rodoviário. Espera-se que os resultados deste trabalho contribuam para suprir, pelo menos em parte, as lacunas de informação quer sobre a composição de várias granulometrias de PM, quer sobre fontes e processos de formação em atmosferas urbanas. Como a exposição a poluentes do ar ultrapassa o controle dos indivíduos e exige ação das autoridades públicas a nível nacional, regional e até mesmo internacional, é importante propor medidas mitigadoras focadas nas principais fontes de emissão identificadas.One of the major factors which adversely affect environmental quality in many cities all over the world is particulate matter (PM) air pollution, with deep negative impacts on human health, climate, buildings, and ecosystems. Many studies conducted in urban areas have been focused only on respirable fractions (PM10 and PM2,5). However, the environmental effects, the formation processes and the source assignment depend greatly on the particle size distribution. In previous studies, attention has been greatly focused on polyaromatic hydrocarbons (PAHs), because of their carcinogenicity. The information available on the particle size distributions for other compounds is rather scarce. Therefore, this study consists in obtaining time series with a sizesegregated detailed chemical composition of PM for differently polluted urban sites in the Iberian Peninsula (Madrid and Lisbon). Taking into account that vehicles represent one of the main emission sources in urban environments, a more detailed characterisation of these emissions was performed by carrying out a sampling campaign in a road tunnel (Marquês de Pombal, Lisbon). Sampling campaigns in both cities were carried out during one month in summer and winter, in two different urban sites. One sampling site was located at a heavy traffic street and other in a urban background site. In, the tunnel sampling took place every 2 days during weekdays, for a total of five days. In Madrid and in the tunnel, PM was collected with a high volume sampler equipped with a PM10 size selective inlet and a cascade impactor with four size fractions: 10-2,5, 2,5-0,95, 0,95-0,49 e < 0,49 μm. In Lisbon, a cascade impactor with two size (10-2,5 and < 2,5 μm) was used. The samples were chemically analysed and the concentrations of carbonaceous compounds (OC, EC and carbonates), water soluble ions (Cl−, NO3−, SO42−, Na+, NH4+, K+, Mg2+,Ca2+), metals and organic compounds were obtained. In Madrid, PM10 average mass concentrations of roadside samples were 44 and 48% higher than at the urban background in summer and winter, respectively. Coarse fraction and PM0,5 concentrations were higher in summer than in winter due to unusual weather conditions. In summer, the sampling was held in a month with high temperatures and with various African dust outbreaks. In winter, low temperatures and precipitation as rain or snow, were registered. The most common synoptic meteorological situations, including those causing the transport of African dusty air masses, were identified in both seasons. Whether the PM10 mass or the highest concentrations of EC and OC were found predominantly in the ultrafine size fraction at both sites. In the remaining fractions no seasonal trend was observed. Secondary organic carbon (SOC) showed a clear seasonal pattern, with much higher concentrations in summer than in winter in both places. From the ion balances, it was observed that, in summer, the formation of secondary inorganic compounds included an unusual enrichment in Ca2+ in the submicrometer fraction, either at roadside or at urban background. Alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and fatty acids were identified and quantified, accounting for 0,26 and 0,11 μg m−3 in summer, and winter, respectively, at the roadside and for 0,28 and 0,035 μg m−3 at the urban background. Different organic compounds presented apparently different seasonal characteristics, reflecting distinct emission sources, such as vehicle exhausts and biogenic inputs. The benzo[a]pyrene equivalent concentrations were lower than 1 ng m-3, The estimated carcinogenic risk was low. In summer, the highest enrichments of metals occurred in the submicrometer fraction, and in winter in the coarse fraction. In summer, enrichments were ≥ 80% for Mn, Ni, Cu, Zn, Cd, Sb and Co, and in winter, these tracers traffic emissions were lower, except for Zn. In Lisbon, the average concentration of PM10 was 48 μg m-3 in summer and 44 μg m-3 in winter at the roadside and 27 μg m-3 and 26 mg m-3 at the urban background. The average ratio PM2,5/PM10 was 65% in summer and 44% in winter at the roadside and 62% and 59% in urban background. This suggests that PM2,5 is a major contaminant affecting urban air quality in the city centre of Lisbon. Inside the tunnel, most of the aerosol mass was concentrated in submicrometer (65%) size fractions. The average mass of particles in the tunnel was more than 30 times higher than outside, suggesting an aerosol origin almost exclusively in fresh emission vehicles. However, three main groups of compounds were broken down: carbonaceous, soil and mechanical wear from vehicles. Cu seems to be a good tracer for wearing emissions from road traffic. A highly linear constant ratio in all size ranges between the levels of Cu and the concentrations of Fe, Mn, Sn and Cr, indicates a single common origin across all size ranges. Cu levels correlate strongly with Fe, Mn, Sn and Cr, showing a highly linear constant ratio in all size ranges. This suggests an unique origin going through all sizes. Ratios of Cu with other elements can be used to source apportion the trace elements present in urban atmospheres, mainly on what concerns coarse aerosol particles. The ratio OC/EC, which reflects the composition of combustion emissions from vehicles, ranged between 0,3 and 0,4 inside the tunnel. The OC/EC minimum ratios observed at both sites were found to be between those of the tunnel and those of urban background air, suggesting that minimum values commonly obtained for this parameter in open urban atmospheres over-predict the direct emissions of OC from road transport. The results of this work will contribute to cover a lack of information on the composition of PM in different sizes, sources and formation processes in urban atmospheres. As exposure to air pollutants is largely beyond the control of individuals and requires action by public authorities at national, regional and even international, it is important to propose mitigation measures focused on the main emission sources identified

Lindqvist versus Keggin-Type Polyoxometalates as Catalysts for Effective Desulfurization of Fuels

A correlation between polyoxotungstate structures and their catalytic performance for oxidative desulfurization processes was investigated. Bridged lanthanopolyoxometalates that incorporate identical metallic centers with Keggin- Eu[PW11O39]11− and Lindqvist-type [Eu(W5O18)2]9− structures were used as catalysts for the oxidation of the most representative refractory sulfur compounds. Both compounds were able to desulfurize a multicomponent model diesel under sustainable conditions, i.e., using ionic liquid as an extraction solvent and hydrogen peroxide as an oxidant. However, the Lindqvist catalyst appeared to achieve complete desulfurization faster than the Keggin catalyst while using a lesser amount of catalyst and oxidant. Furthermore, the reusable capacity of the Lindqvist-type [Eu(W5O18)2]9− was confirmed for consecutive oxidative desulfurization processes. The contribution of the lanthanide metallic center for the catalytic performance of these compounds was investigated by studying the analogous [TB(W5O18)2]9− compound. Identical desulfurization efficiency was obtained, even reusing this catalyst in consecutive reaction cycles. These results indicate that the active catalytic center of these compounds is probably related to the octahedral tungsten centers. However, a higher number of tungsten centers in the polyoxometalate structure did not result in higher catalytic activity

Advanced Technologies Conciliating Desulfurization and Denitrogenation to Prepare Clean Fuels

The removal of sulfur- and nitrogen-containing compounds present in fuels is and will be crucial to accomplish actual strict regulations to avoid environmental and humanity health adversities. The conventional hydrodesulfurization and hydrodenitrogenation processes conducted by refineries are limited due to severe operating conditions, and even more importantly, they are inefficient for simultaneously removing nitrogen- and sulfur-containing compounds in fuels. On the other hand, non-hydrogen technologies are beneficial in terms of mild operating conditions, and during the last two decades, some successful works have shown that these can be highly effective at efficiently removing both sulfur- and nitrogen-containing compounds from liquid fuels. For more than four decades, extensive research (thousands of publications since the 1980s) has been dedicated to developing remote desulfurization technologies without taking into consideration the presence of a complex fuel matrix, or even taking into account the presence of other harmful pollutant elements, such as nitrogen. Even more recently, several effective non-hydrogen denitrogenation processes have been reported without considering the presence of sulfur compounds. This review paper is a reflection on the limited work that has been successfully performed to simultaneously remove sulfur- and nitrogen-containing compounds from fuels. An evaluation of different methodologies (adsorption, extraction, oxidative (photo)catalysis, ultrasound-assisted oxidation) is presented here. Furthermore, this review intends to define new future strategies that will allow the design of more suitable and economical technologies, effectively conciliating desulfurization and denitrogenation processes to produce more sustainable fuels

Organic composition of size segregated atmospheric particulate matter, during summer and winter sampling campaigns at representative sites in Madrid, Spain

Madrid, the largest city of Spain, has some and unique air pollution problems, such as emissions from residential coal burning, a huge vehicle fleet and frequent African dust outbreaks, along with the lack of industrial emissions. The chemical composition of particulate matter (PM) was studied during summer and winter sampling campaigns, conducted in order to obtain size-segregated information at two different urban sites (roadside and urban background). PM was sampled with high volume cascade impactors, with 4 stages: 10-2.5, 2.5-1, 1-0.5 and <0.5μm. Samples were solvent extracted and organic compounds were identified and quantified by GC-MS. Alkanes, polycyclic aromatic hydrocarbons (PAHs), alcohols and fatty acids were chromatographically resolved. The PM1-2.5 was the fraction with the highest mass percentage of organics. Acids were the organic compounds that dominated all particle size fractions. Different organic compounds presented apparently different seasonal characteristics, reflecting distinct emission sources, such as vehicle exhausts and biogenic sources. The benzo[a]pyrene equivalent concentrations were lower than 1ngm-3. The estimated carcinogenic risk is low.F. Mirante thanks the Portuguese Science Foundation for financial support of the training period at CIEMAT, as well for the PhD grant SFRH/BD/45473/2008. This work has also been partially carried out under the framework of the Acción IntegradaPT2009-0151, CGL2011-27020 project, funded by the Spanish Ministry of Science and Innovation and Action no. E-130/10 funded by CRUP. An acknowledgement is also given to everybody who helped during the sampling campaigns.publishe

Infundibuloneurohipofíse: Diagnóstico Diferencial da Diabetes Insípida Caso Clínico

Os diagnósticos diferenciais da forma central de diabetes insípida são vários: traumatismo» infecção malformação, neoplasia, situações inflamatórias diversas. Progressivamente» o número de casos considerado como diabetes insípida idiopática tem vindo a diminuir com a melhoria dos meios imagiológicos, nomeadamente Ressonância Magnética Nuclear. Descreve-se o caso de uma adolescente com diabetes insípida central» associado a alterações na Ressonância Magnética Nuclear a nível neurohipafisário, cuja evolução sugere o diagnóstico infundibuloneurohipofisite

Organic speciation of aerosols from wildfires in central Portugal during summer 2009

The aim of this study was the detailed organic speciation of fine (PM2.5) and coarse (PM2.5–10) particles and gaseous carbonyl compounds from plumes emitted by wildfires during the summer of 2009 in Portugal. Complementary characterisation of the smoke particulate inorganic fraction, along with emission factors of major trace gases, have already been published in Atmospheric Environment. The detailed speciation of organic compounds in particle samples was carried out by gas chromatography-mass spectrometry after multi-solvent extraction, flash chromatography on silica gel and appropriate derivatisation techniques. PM2.5 constitutes an important fraction of PM10 (PM2.5/PM10 > 80%). Gaseous carbonyls were sampled from the Tedlar bags containing the smoke samples in DNHP cartridges and analysed by high-performance liquid chromatography. A clear predominance of carbonaceous constituents was observed, with OC concentrations always much higher than EC in both particle size fractions (OC/EC >> 7). The chromatographically resolved organics were dominated by diterpenoids, acids, sugars, phenols and aliphatic compounds in both size fractions. Retene, a biomarker of softwood smoke, was the dominant aromatic hydrocarbon in samples. The major anhydrosugar detected was levoglucosan, followed by mannosan and galactosan. Among the measured oxygenated volatile organic compounds, the most abundant was acetaldehyde with EFs (dry basis) between 1.03 and 1.87 g kg−1, followed by formaldehyde with values in the range of 0.09–0.96 g kg−1. Propionaldehyde was the less abundant carbonyl, with values in the range of 0.03–0.17 g kg−1.publishe

An Effective Hybrid Heterogeneous Catalyst to Desulfurize Diesel: Peroxotungstate@Metal–Organic Framework

A peroxotungstate composite comprising the chromium terephthalate metal&ndash;organic framework MIL-101(Cr) and the Venturello peroxotungstate [PO4{WO(O2)2}4]3&minus; (PW4) has been prepared by the impregnation method. The PW4@MIL-101(Cr) composite presents high catalytic efficiency for oxidative desulfurization of a multicomponent model diesel containing the most refractory sulfur compounds present in real fuels (2000 ppm of total S). The catalytic performance of this heterogeneous catalyst is similar to the corresponding homogeneous PW4 active center. Desulfurization efficiency of 99.7% was achieved after only 40 min at 70 &deg;C using H2O2 as an oxidant and an ionic liquid as an extraction solvent ([BMIM]PF6, 2:1 model diesel/[BMIM]PF6). High recycling and reusing capacity was also found for PW4@MIL-101(Cr), maintaining its activity for consecutive oxidative desulfurization cycles. A comparison of the catalytic performance of this peroxotungstate composite with others previously reported tungstate@MIL-101(Cr) catalysts indicates that the presence of active oxygen atoms from the peroxo groups promotes a higher oxidative catalytic efficiency in a shorter reaction time

Measurement of trace gases and organic compounds in the smoke plume from a wildfire in Penedono (central Portugal)

Gas and particulate fractions were measured simultaneously from a wildfire in Penedono, central Portugal, which occurred in summer 2009. The total volatile hydrocarbons (THC) and carbon oxides (CO2 and CO) collected in Tedlar bags were measured using automatic analysers with flame ionisation and non-dispersive infrared detectors, respectively. Carbonyls (formaldehyde and acetaldehyde) were sampled from the Tedlar bags in DNHP cartridges and analysed by high-performance liquid chromatography. Fine (PM2.5) and coarse (PM2.5-10) smoke particles were collected sequentially, on pre-fired quartz fibre filters, with a portable high-volume sampler. The detailed speciation of organic compounds in smoke samples was carried out by gas chromatography-mass spectrometry. The organic and elemental carbon content of particulate matter was analysed by a thermal-optical transmission technique. Average emission factors of 1.86 ± 0.80 and 0.063 ± 0.066 g kg−1 (dry basis) were obtained for acetaldehyde and formaldehyde, respectively. The THC, CO, CO2, PM2.5, PM10, OC and EC emission factors (g kg−1 fuel burned, dry basis) were 260 ± 88, 268 ± 92, 1200 ± 172, 37 ± 12.2, 40 ± 12.6, 21 ± 6.7 and 0.44 ± 0.21, respectively. The chromatographically resolved organics included n-alkanes, n-alkenes, n-alkanoic acids, n-di-acids, unsaturated fatty acids, phenolic compounds, ketones, steroids, di- and triterpenoids, PAHs, with retene as the major compound, oxygenated PAH and anhydrosugars.publishe

Lindqvist@Nanoporous MOF-Based Catalyst for Effective Desulfurization of Fuels

An effective and sustainable oxidative desulfurization process for treating a multicomponent model fuel was successfully developed using as a heterogeneous catalyst a composite material containing as an active center the europium Lindqvist [Eu(W5O18)2]9− (abbreviated as EuW10) encapsulated into the nanoporous ZIF-8 (zeolitic imidazolate framework) support. The EuW10@ZIF-8 composite was obtained through an impregnation procedure, and its successful preparation was confirmed by various characterization techniques (FT-IR, XRD, SEM/EDS, ICP-OES). The catalytic activity of the composite and the isolated EuW10 was evaluated in the desulfurization of a multicomponent model fuel containing dibenzothiophene derivatives (DBT, 4-MDBT and 4,6-DMDBT) with a total sulfur concentration of 1500 ppm. Oxidative desulfurization was performed using an ionic liquid as extraction solvent and aqueous hydrogen peroxide as oxidant. The catalytic results showed a remarkable desulfurization performance, with 99.5 and 94.7% sulfur removal in the first 180 min, for the homogeneous active center EuW10 and the heterogeneous EuW10@ZIF-8 catalysts, respectively. Furthermore, the stability of the nanocomposite catalyst was investigated by reusing and recycling processes. A superior retention of catalyst activity in consecutive desulfurization cycles was observed in the recycling studies when compared with the reusing experiments. Nevertheless, the nanostructure of ZIF-8 incorporating the active POM (polyoxometalate) was shown to be highly suitable for guaranteeing the absence of POM leaching, although structural modification was found for ZIF-8 after catalytic use that did not influenced catalytic performance