The catalytic esterification reaction was used to decrease total acid number(TAN) of crude oil by converting naphthenic acids to naphthenic acid esters in the presence of Zn-Al hydrotalcite used as the catalyst and gl...The catalytic esterification reaction was used to decrease total acid number(TAN) of crude oil by converting naphthenic acids to naphthenic acid esters in the presence of Zn-Al hydrotalcite used as the catalyst and glycol used as the reactant. The crude oil and its corresponding esterified oil were characterized by the negative-ion electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). Six acidic class species, O_2, O_1, N_1, N_2, N_1O_1 and N_1O_2 were assigned in the negative-ion spectrum both in the crude oil and its esterified oil. Among the identified acidic compounds, the O2 class was dominant. The relative abundance of O_2 class species was much higher than other acidic class species in crude oil, while it was significantly decreased after esterification. The most abundant O_2 class species had a carbon number of 30-34 and a double-bond equivalence(DBE) value of 5 before and after esterification. It could be concluded that the naphthenic acids in crude oil can be esterified to lower its TAN value, and each of them seems to exhibit identical esterification efficiency approximately due to the similar DBE versus the-carbon number distribution before and after esterification.展开更多
Three high-acidity crudes,Dar,SZ36-1,and QHD326,were separated through distillation into several fractions,including diesel distillates,and VGOs.Samples were characterized by negative-ion ESI FT-ICR MS.The O 2 class s...Three high-acidity crudes,Dar,SZ36-1,and QHD326,were separated through distillation into several fractions,including diesel distillates,and VGOs.Samples were characterized by negative-ion ESI FT-ICR MS.The O 2 class species (petroleum carboxylic acids),which have a close relationship with corrosion of equipment caused by high-acidity crudes,were put in the focus of attention and were discussed in this paper.Monocyclic,bicyclic,and tricyclic naphthenic acids are the main types of petroleum carboxylic acids in naphthenic-base crudes (SZ36-1 and QHD326).But the main types of petroleum carboxylic acids in paraffinic-base crude (Dar) are aliphatic acids and monocyclic naphthenic acids.The O 2 class species in SZ36-1 and QHD326 are distributed in a wider range and have bigger DBE value (double-bond equivalence value) and carbon number than Dar.Bicyclic naphthenic acids have the highest proportion among petroleum carboxylic acids in diesel distillates,but monocyclic and tricyclic naphthenic acids also occupy a high proportion.Particularly,aliphatic acids in the diesel distillate of Dar still have high proportion among petroleum carboxylic acids.The distribution of petroleum carboxylic acids in VGO is basically identical.The bicyclic naphthenic acids assume the first place (about 25 m%),while the monocyclic and tricyclic naphthenic acids take the next place.The comparison of petroleum carboxylic acids in diesel distillates and VGOs has revealed that the molecules of carboxylic acids in VGOs are not only bigger but also more complicated.展开更多
Dissolved organic matter(DOM)derived from various composts can promote significant changes of soil properties.However,little is known about the DOM compositions and their similarities and differences at the molecular ...Dissolved organic matter(DOM)derived from various composts can promote significant changes of soil properties.However,little is known about the DOM compositions and their similarities and differences at the molecular level.In this study,the molecular compositions of DOM derived from kitchen waste compost(KWC),green waste compost(GWC),manure waste compost(MWC),and sewage sludge compost(SSC)were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS).The molecular formulas were classified into four subcategories:CHO,CHON,CHOS,and CHONS.The KWC,MWC,and SSC DOM represented the highest fraction(35.8%-47.4%)of CHON subcategory,while the GWC DOM represented the highest fraction(68.4%)of CHO subcategory.The GWC DOM was recognized as the nitrogen-and sulfurdeficient compounds that were less saturated,more aromatic,and more oxidized compared with other samples.Further analysis of the oxygen,nitrogen-containing(N-containing),and sulfur-containing(S-containing)functional groups in the four subcategories revealed higher organic molecular complexity.Comparison of the similarities and differences of the four samples revealed 22.8%ubiquitous formulas and 17.4%,11.1%,10.7%,and 6.3%unique formulas of GWC,KWC,SSC,and MWC DOM,respectively,suggesting a large proportion of ubiquitous DOM as well as unique,source-specific molecular signatures.The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 21206194)
文摘The catalytic esterification reaction was used to decrease total acid number(TAN) of crude oil by converting naphthenic acids to naphthenic acid esters in the presence of Zn-Al hydrotalcite used as the catalyst and glycol used as the reactant. The crude oil and its corresponding esterified oil were characterized by the negative-ion electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). Six acidic class species, O_2, O_1, N_1, N_2, N_1O_1 and N_1O_2 were assigned in the negative-ion spectrum both in the crude oil and its esterified oil. Among the identified acidic compounds, the O2 class was dominant. The relative abundance of O_2 class species was much higher than other acidic class species in crude oil, while it was significantly decreased after esterification. The most abundant O_2 class species had a carbon number of 30-34 and a double-bond equivalence(DBE) value of 5 before and after esterification. It could be concluded that the naphthenic acids in crude oil can be esterified to lower its TAN value, and each of them seems to exhibit identical esterification efficiency approximately due to the similar DBE versus the-carbon number distribution before and after esterification.
文摘Three high-acidity crudes,Dar,SZ36-1,and QHD326,were separated through distillation into several fractions,including diesel distillates,and VGOs.Samples were characterized by negative-ion ESI FT-ICR MS.The O 2 class species (petroleum carboxylic acids),which have a close relationship with corrosion of equipment caused by high-acidity crudes,were put in the focus of attention and were discussed in this paper.Monocyclic,bicyclic,and tricyclic naphthenic acids are the main types of petroleum carboxylic acids in naphthenic-base crudes (SZ36-1 and QHD326).But the main types of petroleum carboxylic acids in paraffinic-base crude (Dar) are aliphatic acids and monocyclic naphthenic acids.The O 2 class species in SZ36-1 and QHD326 are distributed in a wider range and have bigger DBE value (double-bond equivalence value) and carbon number than Dar.Bicyclic naphthenic acids have the highest proportion among petroleum carboxylic acids in diesel distillates,but monocyclic and tricyclic naphthenic acids also occupy a high proportion.Particularly,aliphatic acids in the diesel distillate of Dar still have high proportion among petroleum carboxylic acids.The distribution of petroleum carboxylic acids in VGO is basically identical.The bicyclic naphthenic acids assume the first place (about 25 m%),while the monocyclic and tricyclic naphthenic acids take the next place.The comparison of petroleum carboxylic acids in diesel distillates and VGOs has revealed that the molecules of carboxylic acids in VGOs are not only bigger but also more complicated.
基金the GDAS’Project of Science and Technology Development(No.2019GDASYL-0501005)the Natural Science Foundation of Guangdong Province(No.2018A030310084)+1 种基金a development project of Ronggui’s strategic emerging industries(Ronggui Jingfa[2019]Reference No.19)the Program of Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development,China(No.y809jm1001)。
文摘Dissolved organic matter(DOM)derived from various composts can promote significant changes of soil properties.However,little is known about the DOM compositions and their similarities and differences at the molecular level.In this study,the molecular compositions of DOM derived from kitchen waste compost(KWC),green waste compost(GWC),manure waste compost(MWC),and sewage sludge compost(SSC)were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS).The molecular formulas were classified into four subcategories:CHO,CHON,CHOS,and CHONS.The KWC,MWC,and SSC DOM represented the highest fraction(35.8%-47.4%)of CHON subcategory,while the GWC DOM represented the highest fraction(68.4%)of CHO subcategory.The GWC DOM was recognized as the nitrogen-and sulfurdeficient compounds that were less saturated,more aromatic,and more oxidized compared with other samples.Further analysis of the oxygen,nitrogen-containing(N-containing),and sulfur-containing(S-containing)functional groups in the four subcategories revealed higher organic molecular complexity.Comparison of the similarities and differences of the four samples revealed 22.8%ubiquitous formulas and 17.4%,11.1%,10.7%,and 6.3%unique formulas of GWC,KWC,SSC,and MWC DOM,respectively,suggesting a large proportion of ubiquitous DOM as well as unique,source-specific molecular signatures.The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.
