Coupling hydrothermal liquefaction and aqueous phase reforming for integrated production of biocrude and renewable H2

Lignin-rich stream from lignocellulosic ethanol production was converted into biocrude by continuous hydrothermal liquefaction (HTL) while hydrogen was produced by aqueous phase reforming (APR) of the HTL aqueous by-product. The effects of Na₂CO₃ and NaOH were investigated both in terms of processability of the feedstock as well as yield and composition of the obtained products. A maximum biocrude yield of 27 wt% was reached in the NaOH-catalyzed runs. A relevant amount of dissolved phenolics were detected in the co-produced aqueous phase (AP), and removed by liquid–liquid extraction using butyl acetate or diethyl ether, preserving the APR catalyst stability and reaching an hydrogen yield up to 146 mmol H₂ L⁻¹ AP. Preliminary mass balances integrating HTL and APR showed that the hydrogen provided by APR may account for up to 46% of the hydrogen amount theoretically required for upgrading the HTL biocrude, thus significantly improving the process performance and sustainability.     

反应条件对玉米秸秆水热液化产物分布及特性的影响

利用间歇式生物质水热液化反应釜,通过正交试验设计考察不同反应条件对玉米秸秆水热液化（HTL）的影响,过程参数包括反应温度（250~350℃）,反应时间（0~60 min）和含固量（5%~15%）。从元素组成、官能团分布、主要化学成分以及结构形貌等对玉米秸秆水热液化产物的特性进行了分析。研究结果表明：玉米秸秆水热液化的较优条件为反应温度300℃、反应时间30 min、含固量5%,此时生物原油（BO）、固体残渣（SR）、其他产物（气相和水相产物）的产率以及液化率分别为22.85%、15.02%、62.13%和84.98%。过程参数对玉米秸秆水热液化的产物分布有显著影响。不同反应条件下玉米秸秆组分降解程度不同,生物原油的产率8.31%~22.85%,热值30.56~32.69 MJ/kg,水相产物的总有机碳（TOC）7 711.5~12 336.0 mg/L,固体产物的组成和表面形貌也不同。FT-IR结果显示：生物原油的官能团分布相似,仅某些峰强度有所差异,表明不同水热条件制备的生物原油中化合物种类相似但含量存在差异。GC-MS分析结果显示：生物原油组成包括酚类、酮类、有机酸类、醛类、醇类、含氮化合物和呋喃类等化合物。     

生物原油炼制： 副产物内循环及水热自催化

利用高温高压条件模拟石油生成的生物质水热液化技术可用于制备生物原油,以替代日益枯竭的石油资源,然而副产物处置问题制约了其可持续发展。解决该问题的方法首先是通过水热定向催化调控减少副产物,然后集成各种技术将副产物尽可能原位资源化。基于此并依据生物炼制的思想,本文对一种集成几种水热技术炼制生物原油的模式进行了讨论。依据生物质水热液化副产物的特性,通过对固体产物水热合成制备催化剂、水相产物回用产生有机酸、气体产物分离或彻底氧化后水热还原生产有机酸等,可实现副产物内循环并强化自催化生成生物原油。指出该模式符合绿色化工的理念,对于加快规模化生产可替代石油的生物原油、缓解能源危机具有重要的参考意义。     

Multi‐scale analysis of acoustic emission signals in dense‐phase pneumatic conveying of pulverized coal at high pressure

Acoustic emission technique in conjunction with multiscale processing method has been utilized to investigate the flow behavior of the dense‐phase pneumatic conveying system at high pressure. A clearly defined classification of microscale, mesoscale, and macroscale signals has been put forward with the aid of wavelet transform and V statistics analysis. The detailed signals d₁–d₄, d₅–d₇, d₈–d₁₀ were recomposed into the microscale, mesoscale, and macroscale signals, respectively, which represent microscale particle‐wall interactions, mesoscale interaction between gas phase and solid phase (such as bubbles, plugs, dunes), and macroscale flow‐induced pipe vibration. Further analysis shows that as the mass flow rate of pulverized coal increases, the energy fraction (energy of detailed signal divided by the energy of original signal) of microscale signals decreases while that of mesoscale signals increases, which indicates that particles are more likely to move as particle aggregates than individual particles when mass flow rate increases. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2635–2648, 2016     

Polymorph selection by continuous crystallization

This article is motivated by a remarkable observation reported recently by Myerson, Trout, and co‐workers that continuous crystallization is capable of producing metastable polymorphs in stable steady‐state operation. We explain why this phenomenon occurs and give simple design rules for reproducing it in other polymorphic systems. A linear stability analysis gives simple functions of parameters for which one can continuously produce thermodynamically metastable products based only on the relative polymorph dynamics. We demonstrate agreement with two sets of experimental data; L‐glutamic acid grown from aqueous solution and p‐aminobenzoic acid also grown from aqueous solution. For many polymorphic compounds, engineering a process to produce a desired polymorph is as simple as finding a reasonable operating point for the continuous mixed‐suspension mixed‐product removal crystallization process (temperature, residence time, initial supersaturation, etc.) according to the rules reported in this article. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3505–3514, 2016     

Synthesis,characterization, and properties of amphiphilic block copolymer of acrylamide‐styrene by self‐emulsifying microemulsion method

The copolymerization system of acrylamide (AM) and styrene (St) was acquired by using amphiphilic block copolymer PAM‐b‐PSt with lower molecular weight as polymeric surfactant, and then the microemulsion phase diagram was drawn. The appropriate copolymerization systems were chosen in the phase diagram, and higher molecular weight amphiphilic block copolymers PAM‐b‐PSt were prepared by self‐emulsifying microemulsion method. The chemical composition and structure of the products were analyzed by FTIR, ¹H‐NMR, ¹³C‐NMR, GPC, and UV; the block structure of products was characterized by DSC, and the hydrophobic association property of the products was studied by the fluorescence probe and rotating viscosity measurement. The results showed that O/W microemulsion was also acquired by using the polymeric surfactant; 3 g polymeric surfactant was only used to disperse 0.25 g St into aqueous solution, which showed higher emulsifying efficiency. At the same time, the use of self‐emulsifying microemulsion copolymerizing system can avoid back treatment of small molecular surfactant and the purified block polymer was prepared in one step; the prepared copolymers have good hydrophobic association properties and their aqueous solution showed evident viscosity increment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors

A methodology for the determination of mass transfer resistances of fast reactions in three‐phase mechanically agitated slurry reactors under the reaction conditions is presented. The mass transfer resistances affect significantly the overall mass transfer rate, the design equation and consequently the scale up of the reactor. There is not established methodology to separate the mass transfer resistances under reaction conditions by changing catalyst loading and manipulating the process variables, pressure and agitation speed. This allows to avoid the use of different catalyst particles and give the chance to calculate the mass transfer resistances without caring about the type of catalyst. We calculate each mass transfer resistance under conditions which do not allow to neglect any of the resistances. It is shown that the level off of mass transfer rate which is developed in the plot of mass transfer rate against agitation speed plots is not enough to determine the limiting regime. The hydrogenation of styrene over Pd/C (5% catalyst content) is used as case study to demonstrate the methodology. © 2016 American Institute of Chemical Engineers AIChE J, 63: 273–282, 2017     

Analysis of insect triacylglycerols using liquid chromatography‐atmospheric pressure chemical ionization‐mass spectrometry

An HPLC non‐aqueous reversed‐phase separation system was adapted for analyzing insect triacylglycerols (TAG). The method uses two conventional Nova‐Pak C18 columns connected in series, for a total length of 45 cm. The mobile phase gradient is mixed from acetonitrile and 2‐propanol, and the flow rate is programmed from 1.0 to 0.7 mL/min. TAG are detected by atmospheric pressure chemical ionization‐mass spectrometry. The method ensures efficient separation of isomers and analysis of high‐molecular‐weight TAG with equivalent chain lengths up to 72. The method performance is demonstrated on analysis of TAG isolated from the fat body of the bumblebee Bombus lucorum.     

Application of Aqueous Two‐Phase Systems for the Potential Extractive Fermentation of Cyanobacterial Products

The potential use of aqueous two‐phase systems (ATPS) to establish a viable protocol for the in situ recovery of cyanobacterial products was evaluated. The evaluation of system parameters such as poly (ethylene glycol) (PEG) molecular mass, concentration of PEG and salt was carried out to determine the conditions under which Synechocystis sp. PCC 6803 cell and cyanobacterial products, i.e., β‐carotene and lutein, become concentrated in opposite phases. PEG‐phosphate ATPS proved to be unsuitable for the recovery of cyanobacterial products due to the negative effect of the salt upon the cell growth. The use of ATPS PEG‐dextran (6.6 % w/w PEG 3350, 8.4 % w/w dextran 66900, TLL 17.3 % w/w, V_R 1.0, pH 7) and (4.22 % w/w PEG 8000, 9.77 % w/w dextran 66900, TLL 18 % w/w, V_R 1.0, pH 7) resulted in the growth of cyanobacteria (Synechocystis sp. PCC 6803) and the concentration of lutein in opposite phases. However, β‐carotene was seen to concentrate in the top phase together with the biomass. The results reported here demonstrate the potential application of ATPS to establish the conditions for an extractive fermentation prototype process for the recovery of cyanobacterial products.     

Synthesis and application of sodium 2‐acrylamido‐2‐methylpropane sulphonate/N‐vinylcaprolactam/divinyl benzene as a high‐performance viscosifier in water‐based drilling fluid

Aiming at good thickening ability and temperature resistance in water‐based drilling fluid, a novel copolymer viscosifier (SDKP) of sodium 2‐acrylamido‐2‐methylpropane sulfonate (NaAMPS) with N‐vinylcaprolactam (NVCL) and cross‐linking divinylbenzene (DVB) was prepared by micellar radical polymerization. The composition and molecular structure of optimal SDKP under the optimum reaction conditions was characterized by FT‐IR, ¹H‐NMR, and elemental analysis, and the molecular weight was determined by GPC. Thermal gravimetric analysis showed that the SDKP was even stable when the temperature was not higher than 330 °C. The performance of SDKP as viscosifier for aqueous, brines, and saturated brine bentonite drilling fluid was evaluated before and after aging tests at 230 °C for 16 h. The evaluation results indicated that the SDKP had excellent thickening ability, thermal resistant, and salt tolerance. HTHP rheology test showed that the SDKP containing drilling fluids displayed a thermo‐thickening effect in temperature range of 150 to 180 °C, which was beneficial to increase the viscosity and strength of fluids at high temperatures. Shear test showed that the SDKP illustrated a similar shear thinning to xanthan gum. ESEM observations demonstrated that the continuous three‐dimensional network was formed in the SDKP aqueous and brines solution, which was probably the main reason for its excellent thickening properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44140.     

Mechanistic insights into aqueous phase propanol dehydration in H‐ZSM‐5 zeolite

Aqueous phase dehydration of 1‐propanol over H‐ZSM‐5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulations of the mimicking aqueous phase H‐ZSM‐5 unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol–propanol, the propanol–water, and the trimeric propanol–propanol–water complexes are formed at high propanol concentrations in aqueous phase, which provide a kinetically feasible dehydration reaction channel of 1‐propanol to propene. The calculation results indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration. © 2016 American Institute of Chemical Engineers AIChE J, 63: 172–184, 2017     

Polarity‐reversal‐producing phase transfer of hydrophilic silver nanoclusters capped by a hyperbranched polymer from water to nonpolar organic solvents

Hyperbranched poly(ethylene imine) (PEI)‐capped Ag nanoclusters, synthesized starting from an aqueous environment, dispersed well in water and most polar organic solvents. However, with the addition of 1,4‐dioxane, the PEI‐capped Ag nanoclusters could be separated completely to obtain hydrophilic and hydrophobic Ag nanoclusters. Through this facile method, the successful phase transfer of PEI‐capped Ag nanoclusters from the aqueous phase to the nonpolar organic phase, such as from water to carbon tetrachloride, chloroform, and methylene bichloride, was easily realized. The polarity reversal of Ag nanoclusters were considered to be associated with the conformational change of PEI on the basis of the hydrophobic methylene groups of polymer backbone facing the external side or internal side, and this polarity reversal was irreversible. Moreover, PEIs with higher molecular weights showed a higher efficiency of phase transfer of the Ag nanoclusters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43206.     

Influence of curing sequence on phase structure and properties of bisphenol A‐aniline benzoxazine/N,N′‐(2,2,4‐trimethylhexane‐1,6‐diyl) bis (maleimide)/imidazole blend

The effects of different catalysts on the curing sequences of bisphenol A‐aniline benzoxazine (BA‐a)/N,N′‐(2,2,4‐trimethylhexane‐1,6‐diyl) bis (maleimide) (TBMI) blends were studied, and the influence of curing sequences on the phase structure and properties of products was discussed. In BA‐a/TBMI/adipic acid, BA‐a homopolymerized first, followed by the copolymerization between TBMI and ring‐opened benzoxazine. This curing sequence led to strong copolymerization, which limited the movement of components and resulted in homogeneous structures of the final products. However, in BA‐a/TBMI/imidazole, TBMI homopolymerized firstly, followed by the homopolymerization of BA‐a. BA‐a and TBMI hardly copolymerized, and the products presented phase‐separated (bi‐continuous phase) structures finally. The degree of copolymerization and phase structures of products differed due to different curing sequences when different catalysts were used. Furthermore, the product with phase‐separated structures had improved thermal property and toughness compared to those of the product with homogeneous structures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43259.     

国内外生物原油技术开发现状与分析

通过生物原油加氢改质生产清洁汽柴油是未来生物燃料技术的重要发展方向。本文介绍了生物原油的组成、特性及生物原油技术的研发现状,重点对快速热裂解、催化裂解生产生物原油及其加氢改质技术进展进行了探讨分析。结论指出,国内外生物原油及其改质精制生产清洁运输燃料技术目前仍处于研究开发阶段,离工业化生产还有很大的差距,预计未来生物原油在石油替代进程中必将占有重要地位,我国要加快生物原油技术研发步伐,争取早日实现工业化生产,以满足市场日益增长的交通燃料需求。     

Dissolution of starch in urea/NaOH aqueous solutions

Dissolution of starch in urea/NaOH aqueous solutions was studied by using polarizing microscope and viscometry. The experimental results revealed that starch could dissolve in urea (2–20 wt %) and NaOH (10–1 wt %) aqueous solutions at temperature ranging from ?12 to 25 °C, where the optimized dissolution condition was in the aqueous solution of mixed urea 14% and NaOH 4% at 0 °C for 30 min or above. Under the conditions, the starch solubility could be 99.0 and 92.1% as the starch weight percent was 1 and 10%, respectively. Measurements for the molecular weight and amylose content of the starch before and after the dissolution indicated that there was no serious degradation during the process. The results from determinations of X‐ray diffraction, Fourier transform infrared, and rapid visco analysis revealed that the recovered starch from the starch solutions was an amorphous solid with a part of V‐type pattern (single‐helix). The urea/NaOH aqueous solvent may have potential significance for starch processing and modification. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43390.     

Experimental methods in chemical engineering: Thermogravimetric analysis—TGA

Thermogravimetric analysis (TGA) is a quantitative analytical technique that monitors the mass of a sample from 1 mg to several g as a furnace ramps temperature to as high as 1600°C under a stable or changing gas flow. The first gravimetric test was in 27 BC when Vitruvius measured limestone's change of mass as it calcined to lime. In modern chemical engineering, researchers apply the technique to derive conversions, kinetics, and mechanisms for any process with a change of mass by isothermal, non-isothermal, and quasi-isothermal methods. The mass drops as the sample decomposes, volatile compounds evaporate, or the oxidation state decreases, while in reactive environments (with O₂, for example), the mass of transition metals may increase. TGA is incapable of detecting phase transitions, polymorphic transformations, or reactions for which mass is invariant. DSC or DTA couple with TGA to help deconvolute a DSC plot by separating physical changes from chemical changes. Evolved gas analysis techniques monitor the gaseous products exiting the TGA furnace on-line as the temperature ramps. A bibliometric map of keywords from articles citing TGA indexed by Web of Science in 2016 and 2017 identified five research clusters: nanoparticles, performance, and films; crystal structures, acid, and oxidation; composites, nanocomposites, and mechanical properties; kinetics, pyrolysis, and temperature; and adsorption, water and wastewater, and aqueous solutions. This review provides an overview of the basic principles of modern TGA.     

Mathematical approach to compute the molecular composition of hydrothermal liquefaction-derived renewable crude oil

Hydrothermal liquefaction (HTL), a thermo-chemical conversion process, uses water as a reaction medium at elevated pressure and temperature, to convert biomass to renewable liquid fuel and recovers fertilizer-rich water. To assess the techno-economic screening of HTL oils from various feedstock, it is crucial to have information on molecular composition of the feed and products. There are limitations of existing analytical methods to identify and quantify all the molecules present in the bio-fuel. Therefore, there is a need to find alternate ways to quantify the molecular composition of feed and expected products. The modeling work on bio-oil is developed and validated on mathematical approach using simple analytical results like CHNO along with structural analysis of oil like Fourier-transform infrared, nuclear magnetic resonance analysis for HTL derived oil from microalgae. This mathematical framework is further extended to predict the molecular composition of oil obtained from HTL of feedstocks like mixed plastic waste, sludge, and so on. A multi-dimensional molecular matrix is developed based on the distributions of side chains, aromatic rings, and olefinic carbon on top of core molecules. The parameters of the distributions are estimated computationally using global optimization algorithm (genetic algorithm) and local optimization algorithm to predict a mixture composition that matches closely with bulk properties of the product.     

Considerations on film reactivity in the aqueous biphasic hydroformylation

In experiments and kinetic models it was shown that the reaction rate of the biphasic aqueous hydroformylation of 1‐octene is linear dependent on the created interfacial area. This phenomenon is directly linked to the question whether the reaction takes place in the bulk phase and is mass transfer limitation or at the surface which would mean an increase of reaction space. To evaluate the place of reaction a mass transfer analysis has been carried out. No mass transfer limitation for the gaseous components carbon monoxide and hydrogen as well as the olefin 1‐octene was determined for the aqueous catalyst phase by calculating the Hatta numbers. With this observation it is possible to exclude the mass transfer as a potential influence and hence the aqueous bulk as the place of reaction. Thus the reaction is most probably surface active. This can be either explained the increase in film volume fraction where non‐polar substrate as well as polar catalyst complex is present or through an increased catalyst concentration at the surface through dipole moment fluctuations. © 2017 American Institute of Chemical Engineers AIChE J, 63: 161–171, 2018     

Mass transfer into/from nanofluid drops in a spray liquid‐liquid extraction column

The performance of a spray liquid‐liquid extraction column at two mass‐transfer directions was experimentally studied in the presence of silica nanoparticles. Toluene‐based nanofluid drops containing 0.0005–0.01 vol % silica nanoparticles were dispersed in aqueous phase and acetic acid (AA) transfer between phases was investigated. The experiments were performed at fixed volumetric flow rates of dispersed and continuous phases. Maximum enhancement of 47.4% and 107.5% in overall mass‐transfer coefficient, respectively, for mass‐transfer direction of dispersed to continuous phase and vice versa were achieved for drops with 0.001 vol % silica nanoparticles. These enhancements can be referred to Brownian motion of nanoparticles and induced microconvection. The results showed that nanoparticles are more effective in augmenting AA transfer from continuous to dispersed phase. Probable reason is that smaller diameter and lower internal turbulence of drops in this transfer direction increase dispersed phase resistance potential to be manipulated by Brownian motion of nanoparticles. © 2015 American Institute of Chemical Engineers AIChE J, 62: 852–860, 2016     

Kinetics of homogeneous 5‐hydroxymethylfurfural oxidation to 2,5‐furandicarboxylic acid with Co/Mn/Br catalyst

2,5‐furandicarboxylic acid (FDCA) is a potential non‐phthalate based bio‐renewable substitute for terephthalic acid‐based plastics. Herein, we present an investigation of the oxidation rate of 5‐hydroxymethylfurfural (HMF) to FDCA in acetic acid medium using Co/Mn/Br catalyst. Transient concentration profiles of the reactant (HMF), intermediates [2,5‐diformylfuran (DFF), 5‐formyl‐2‐furancarboxylic acid (FFCA)], and the desired product (FDCA) were obtained for this relatively fast reaction in a stirred semi‐batch reactor using rapid in‐line sampling. Comparison of the effective rate constants for the series oxidation steps with predicted gas–liquid mass transfer coefficients reveals that except for the FFCA → FDCA step, the first two oxidation steps are subject to gas–liquid mass transfer limitations even at high stirrer speeds. Novel reactor configurations, such as a reactor in which the reaction mixture is dispersed as fine droplets into a gas phase containing oxygen, are required to overcome oxygen starvation in the liquid phase and further intensify FDCA production. © 2016 American Institute of Chemical Engineers AIChE J, 63: 162–171, 2017