The unusual properties of high mass materials from coal-derived liquids

This short paper highlights the unusual properties of the high-mass material of coal liquids isolated by their insolubility in pyridine and solubility in NMP. The separation has been achieved by a column chromatography method. One gram quantity have been processed and near quantitative recovery of the sample as fractions has been achieved. This fractionation permitted recourse to a broad range of analytical methods, including some (e.g. ¹³C NMR), which require large sample sizes. Multiple macro analyses have been undertaken, using elemental analysis, TGA proximate analysis, NMR and FT-ir in addition to the micro-analytical methods used previously—pyrolysis-gc-ms, SEC, UV-fluorescence, probe-ms and MALDI-ms. The fractions show increasing concentrations of large molecular mass material with increasing polarity of successive eluents used in the fractionation. Evidence from solid-state ¹³C NMR and UV-fluorescence spectroscopy show progressive structural changes with increasing apparent molecular mass.     

Size exclusion chromatographic approach for the evaluation of processes for upgrading heavy petroleum

A new application of size exclusion chromatography for the evaluation of processes for upgrading heavy crudes is described. The comparison of the elution curves of a feedstock of heavy crude, selected for an upgrading process, is made with the resulting products of the process. A quantitative assessment of the extent of the improvement as a result of the hydrogenation in the crude is presented by defining an algorithm which measures the conversion of material up to 550 °C. The defined conversion is correlated with conventional crude properties and there is a linear relation between the conversion obtained by s.e.c. and certain selected properties. The results for a number of products are included and the relation between conversion and process conditions is discussed.     

Characterising high mass materials in heavy oil fractions by size exclusion chromatography and MALDI-mass spectrometry

Several petroleum vacuum residues and a Maya asphaltene have been examined using size exclusion chromatography (SEC), using 1-methyl-2-pyrrolidinone as eluent. Aliphatic components are not dissolved in this solvent. All the samples showed a bimodal distribution. Material under the early eluting peak, excluded from column porosity corresponded to apparently very large molecular masses. The later eluting peak corresponded to molecules with a smaller range of masses and was relatively intense. The material excluded from column porosity is concentrated in the heptane-insoluble fraction; the peak of this fraction corresponding to smaller molecules shifted to earlier times than was found for the whole sample. In UV-fluorescence spectrometry, the heptane-insoluble materials did not fluoresce strongly. Materials excluded from column porosity showed no fluorescence, indicating that UV-fluorescence based methods are unable to detect high mass materials. MALDI-mass spectrometry indicated a bimodal distribution for the Maya asphaltene with a mass range up to m/z 40,000. Comparison of the low mass range of the spectrum with the small-size molecules detected by SEC indicated broad agreement for masses up to about 5000 u. However, if the excluded peak of SEC corresponds to the higher mass range up to m/z 40,000, then it is likely that these molecules are adopting three-dimensional conformations. Data from the hydrocracking of heavy oils was used to confirm some of the outlined findings.     

High-temperature simulated distillation GC analysis of petroleum resids and their products from catalytic upgrading over Co–Mo/Al2O3 catalyst

Two petroleum resids and their products from catalytic upgrading were characterized by high-temperature simulated distillation using gas chromatography (HT-SimDis GC) with a capillary column. The atmospheric equivalent boiling points (AEBP) determined by the HT-SimDis GC method in this work reached an end point of 847°C (1557°F). This method successfully analyzed the AEBP distribution of an atmospheric resid and a vacuum resid as well as their products from catalytic hydroprocessing. The analysis of the AEBP distribution vs. reaction temperature revealed that catalytic upgrading not only produced lighter fractions but also created desirable changes in the remaining >540°C fractions. For the runs over a sulfided Co–Mo/Al₂O₃ catalyst, the yields of products with BP range of 540–700°C remained almost constant when the reaction temperature was within 350–400°C but decreased monotonically with further increasing reaction temperature up to 450°C. At 450°C, the 450–540°C fraction was also converted. The extent of catalytic hydrodesulfurization over Co–Mo/Al₂O₃ catalyst increased with temperature from 350 to 450°C.     

定量体积排除色谱用于火药成分分析的研究

研究了定量体积排除色谱分析火药成分的方法,用ＷＡＴＥＲＳ－２４４型高效体积排除色谱仪对火药的成分进行了实验测定,对所得图谱进行了解析,讨论了具有重叠峰成分的分峰方法,给出了一些火药成分的标准曲线。并以单基火药和双迫火药为例将实验结果与化学分析方法结果进行了比较。结果表明,用定量体积排除色谱法能同时分离与测定火药的各种成分操作简单,结果准确,这对火药的生产与研究具有重要的应用价值。     

Surface properties of heavy petroleum distillation residues

Heavy residues of the distillation of oils from different origins and their main constituents (oil, asphalt, resins and asphaltenes) were analysed using various methods: elemental analysis, potentiometry for acid and base content measurement, i.r. spectroscopy for H bonding capacity determination, a spot test for the evaluation of the flocculation tendency of the constituents and either liquid contact angle measurements on compressed powders or inverse gas chromatography for the assessment of the surface free energy of the solid constituents of the residues. The properties of the heavy residues are quite different. In particular, the surface properties depend on the molecular composition (functional group content) of the residues but also on the degree of association of polar and less polar constituents. Clearly the weight ratio of resins and asphaltenes is a significant factor for the surface properties and the stability of heavy residues.     

Control of molecular weight distribution of petroleum pitches via multistage supercritical extraction

Packed-column supercritical extraction (SCE), followed by low-pressure gas stripping, was used to produce a dimer-rich pitch fraction from an oligomeric petroleum pitch, Marathon M-50, of broad molecular weight distribution (MWD). Both solvent-to-pitch ratios (S/P) >5 and a positive retrograde temperature gradient of 380-330 °C at 70 bar were found to reduce significantly the amount of trimer+ oligomers in the overhead product from the SCE column. This monomer- and dimer-rich overhead was subsequently stripped of monomer with gaseous toluene in a second packed column at 380 °C and 1.5 bar to obtain an 80+ mol% dimer product with an overall yield, based on the original feed, of 30%. To our knowledge, this is the first reported fractionation of a dimer-rich cut from a petroleum pitch with a demonstrably low level of both lower and higher mol wt impurities.     

Physico-chemical analysis of five hard bitumens: Identification of chemical species and molecular organization before and after artificial aging

The present paper focuses on a physico-chemical analysis of five different types of bitumens, both before and after aging. These bitumen samples were chosen based on: the original crude oil (straight-run bitumens with different asphaltene and crystallized fraction contents), mode of refining (straight-run vs. half-blown bitumen), and modifier characteristics (straight-run vs. polyphosphoric acid (PPA)-modified bitumen). The aim of this study is to determine both the aging effect on chemical species and the chemical organization as a function of the type of bitumen sample.In order to obtain information on bitumen chemistry, n-heptane precipitation (Standard NF EN 12591), IATROSCAN chromatography (coupling between a thin-layer liquid chromatography on a silica gel and a flame ionization detector), FTIR spectroscopy and differential scanning calorimetry (DSC) have all been used. Size exclusion chromatography under “high-speed” conditions (HS-SEC), which yields information relative to asphaltene associations, was also introduced. Several years of road aging were simulated through 25 h of a pressure aging vessel (PAV) test.The coupling of IATROSCAN chromatography and n-heptane precipitation made it possible to identify and quantify polar resins.In accordance with previous studies, the use of HS-SEC combined with IATROSCAN chromatography indicates that a modification by PPA leads to an increase in asphaltene content and a more dispersed asphaltene structure than that found in pure bitumen. This same conclusion can be drawn from observations of the half-blown bitumen sample. The half-blown bitumen actually contains less asphaltene than one of the straight-run bitumens in the study; furthermore, its asphaltenes are more highly agglomerated. These results demonstrate that asphaltene association does not systematically depend on quantity alone, as its chemical type also enters into play. Moreover, during aging, even though asphaltene content is increasing for all bitumen samples, its agglomeration is still highly dependent on the type of bitumen. It would therefore appear that the presence of crystallized fractions exerts a major influence on this process.     

Molar mass analysis of polyamides-11 and -12 by size exclusion chromatography in HFiP

The SEC analysis of polyamide-11 and polyamide-12 can be conducted free of association and aggregation phenomena when hexafluoroisopropanol + 0.05 mol/L potassium trifluoroacetate are used as the mobile phase. The calibration of the SEC system can be conducted in different ways. As stationary phases non-polar polystyrene and polar perfluoro silicagel were tested. The investigations showed that the polystyrene gel exhibits hydrophobic interactions with the polyamides while with the silicagel selective interactions were not found. Investigating different options for SEC calibration it was found that conventional PMMA calibration does not yield correct results. The universal calibration approach based on PMMA calibration did not work either. Correct molar masses were obtained when the PMMA calibration curve was corrected with data from polyamide blends using a simplex algorithm. Alternatively, calibration can be conducted with broadly distributed polyamides that were first fully characterized by SEC-MALLS. The resulting molar mass distributions for different sets of polyamides were compared with molar masses that were determined directly by SEC-MALLS and excellent correlation was obtained.     

Knowledge of petroleum heavy residue potential as feedstock in refining process using thermogravimetry

In the petroleum industry, previous knowledge of the feedstock's potential to produce light material is an important aspect of refining. For the evaluation of heavy petroleum fractions, thermogravimetry (TG), a thermal analysis technique, is considered a good analytical tool to determine the thermal behavior of these fractions at high temperatures. In the present work, TG analyses were made of petroleum distillation residues from different Brazilian oils. The apparent cracking activation energy of saturates, aromatics, resins and asphaltenes was also determined by TG. Saturates and aromatics showed values of 80-120 kJmol^− 1 at low conversions (< 0.3) and of 120-220 kJ mol^− 1 at high conversions (> 0.3). The thermal cracking activation energy of resins and asphaltenes occurred between 220-300 kJ mol^− 1, i.e., at higher values than those of aromatic and saturated fractions. This paper discusses the prediction of carbonaceous residue based on thermal analysis.     

Characterization of liquid products from the co-cracking of ternary and quaternary mixture of petroleum vacuum residue, polypropylene, Samla coal and Calotropis Procera

The co-cracking of the petroleum vacuum residue (XVR) with polypropylene (PP), Samla coal (SC) and Calotropis procera (CL) has been carried out in a batch reactor under isothermal conditions at atmospheric pressure. The liquids obtained by co-cracking have been characterized by Fourier transform infrared spectroscopy, high performance liquid chromatography, ¹H nuclear magnetic resonance (NMR), ¹³C NMR, gel permeation chromatography (GPC), and inductively coupled argon plasma analyses. It was found that the liquid products obtained from the co-cracking of ternary and quaternary mixtures of the petroleum vacuum residue with polypropylene, coal and C. procera contained less than 1 ppm of Ni and V. The HPLC analyses indicates that the liquids obtained from the cracking of ternary mixture of XVR+PP+CL were mainly aliphatic in nature (saturates content 87.4%). NMR analyses showed that the aromatic carbon contents decreased (15.0%) in the liquid products derived from the co-cracking of quaternary mixtures of XVR+PP+SC+CL compared to their theoretical averages (taking the averages of aromatic carbon contents of the liquids from XVR, PP, SC and CL individually). The overall results indicated that there exists a definite interaction of reactive species when XVR, PP, SC and CL were co-cracked together.     

Synthesis and Chromatographic Separation of Monomethoxypolyethylene Glycol Modified Insulin

Abstract

Insulin was modified with monomethoxypolyethylene glycol (MPEG)‐succinimidyl succinate and succinimidyl ester of carboxymethyl MPEG. Effects of reaction solvents, initial molar ratio of MPEG derivative to insulin and reaction time on PEGylation of insulin were investigated by 2,4,6‐trinitrobenzenesulfonic acid spectrophotometric assay and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Sephadex G75 size exclusion chromatography (SEC), ion exchange chromatography (IEC) and reversed phase‐high performance liquid chromatography (RP‐HPLC) were applied to separate PEGylated insulin. IEC and RP‐HPLC were proved to be efficient tools on separation of different PEGylated insulin species.     

Termini and main-chain composition of monomethoxy-terminated poly(ethylene glycol) studied by two-dimensional column chromatography

Samples of poly(ethylene glycol) especially those with functionalized ends have dimeric, trimeric, and tetrameric components at twice, three times, and four times as high a molecular weight (MW) as that of the main component. We used two-dimensional column chromatography to evaluate the MW and identify the terminal groups in each component. The first step is high osmotic pressure chromatography to prepare a sufficient amount of fractions that contain different percentages of the multimeric components. In the second step, each of the fractions was characterized by using regular size exclusion chromatography and high-resolution NMR. Decomposition of the chromatogram combined with isolation of the terminal methoxy peak in the NMR spectrum led to unique identification of the terminal groups. We thus found that the monomeric component is monomethoxy-terminated whereas the dimeric and other multimeric components are mostly dihydroxy-terminated.     

A high performance size exclusion chromatographic study on the depth-dependent gradient in the molecular weight of aged triterpenoid varnish films

The depth-profiles of aged triterpenoid resin films, dammar and mastic, were uncovered by optimized krypton fluoride excimer laser ablation (248 nm, 25 ns) and the etched varnishes were examined by high performance size exclusion chromatography (HP-SEC). The use of two detectors monitored the molecular weight distribution across depth as a function of absorbance at ultraviolet (240 nm) and visible (400 nm) light. The absorption of the films at both wavelengths is separated in a small fraction of sesquiterpenoids (200 Da), triterpenoid molecules (400/500 Da), dimerized and oxidized triterpenoid molecules (900–1000 Da) and condensed entities (10–80 kDa) that are formed upon the radical polymerization of polycadinene and cis-1,4-poly-β-myrcene, which are the polymers of dammar and mastic, respectively. The results establish the generation of depth-dependent gradients in radical polymerization, condensation and cross-linking across the depth-profiles of the triterpenoid films as a consequence of aging.     

Characterization of the extracts and residues from CS2-N-methyl-2-pyrrolidinone mixed solvent extraction

The extracts and residues obtained by extraction of five bituminous coals with CS₂-N-methyl-2-pyrrolidinone mixed solvent (1:1 by volume) were characterized at room temperature. The extraction yields were 31.1–63.0% (daf) and the extracts were fractionated into acetone soluble (AS), acetone insoluble-pyridine soluble (PS) and pyridine insoluble-mixed solvent soluble (MS) fractions. The MS fraction, which was the heaviest fraction examined, had higher values of % oxygen, f_a, molecular weight and spin concentration than the corresponding AS and PS fractions, but a similar degree of aromatic condensation. The quantities of volatile matter (daf) in the residues were similar or slightly less than those in the extracts.     

Composition of petroleum heavy ends. 3. Comparison of the composition of high-boiling petroleum distillates and petroleum >675 °C residues

Three ‘heavy ends’ fractions of petroleum are compared and defined as 370–535 °C distillates, 535–675 °C distillates, and >675 °C residues. The distributions of classes of compounds, compound types, molecular weights, and heteroatom content of individual molecules in the heavy ends fractions are discussed.     

Experimental campaign,modeling, and sensitivity analysis for the molecular distillation of petroleum residues 673.15 K+

This research activity proposes a sensitivity analysis of the molecular distillation process by focusing the attention on the response of the overall distillate flow rate under several conditions of distillation temperature and feed flow rate. Specific equations to characterize physicochemical properties of petroleum residues have been formulated by means of ASTM-based experimental campaigns combined with specific optimization techniques.     

Influence of heat and pressure treatment on the rheological behavior of petroleum pitches

Pitch rheological properties are extremely important during the manufacturing process of carbon materials, in mesophase formation, and with regard to the final properties of the carbon products. In this work, pitch samples have been prepared from three different FCC decant oils by heat-treatment, under 0.9 MPa pressure, in a reactor at 390 °C, 410 °C, and 430 °C. These samples were analyzed in a rotational rheometer using a parallel-plate sensor. The rheometric softening points matched the results obtained using conventional equipment and exponential relationships were found to exist between these softening points and the pitch cosity when the former approached 180 °C. The quinoline-insoluble content (QI) has been shown to be more important in increasing the pitch viscosity than the toluene-insoluble content (TI). Oscillatory rheometry analysis has shown that an elastic response is not always found in creep and recovery tests, even when the elastic modulus G′ is dominant over the viscous modulus G′′. Pitch elasticity was found to be independent of the mesophase, and this pitch property was either only observed when the cross-over point occurred at very high frequencies or did not occur at all within the frequency range studied.     

Chromatographic characterisation of aptamer-modified poly(EDMA-co-GMA) monolithic disk format for protein binding and separation

The introduction of aptameric ligands onto disk-monolithic adsorbent, representing a unique strategy for convective isolation of target molecules with high specificity and selectivity, is investigated for the first time. Experimental results showed that the disk monolith possessed a good permeability of 1.67 ± 0.05 × 10^–14 m² (RSD = 3.2%). The aptameric ligand density for the aptamer-modified disk monolith was 480 pmol/uL. Chromatographic analysis of the aptamer disk-monolith efficiency showed an optimum linear velocity of 126 cm/min (≈0.25 mL/min) at room temperatures 25 ± 2°C. The theoretical number of plates corresponding to the optimum linear velocity was 128.2 with an height equivalent to the theoretical plate of 0.022 mm. The disk aptamer-immobilised monolithic system demonstrated good selectivity and isolation of thrombin from non-targets.