Unified Model of Purification Units in Hydrogen Networks

Purification processes are widely used in hydrogen networks of refineries to increase hydrogen reuse. In refineries, hydrogen purification techniques include hydrocarbon, hydrogen sulfide and CO removal units. In addition, light hydrocarbon recovery from the hydrogen source streams can also result in hydrogen purification. In order to simplify the superstructure and mathematical model of hydrogen network integration, the models of different purification processes are unified in this paper, including mass balance and the expressions for hydrogen recovery and impurity removal ratios, which are given for all the purification units in refineries. Based on the proposed unified model, a superstructure of hydrogen networks with purification processes is constructed.

Optimization of hydrogen networks with multiple impurities and impurity removal

To explore the effect of removing different impurities to hydrogen networks, an MINLP model is proposed with all matching possibilities and the trade-off between operation cost and capital cost is considered. Furthermore,the impurity remover, hydrogen distribution, compressor and pipe setting are included in the model. Based on this model, the impurity and source(s) that are in higher priority for impurity removal, the optimal targeted concentration, and the hydrogen network with the minimum annual cost can be identified. The efficiency of the proposed model is verified by a case study.

Improving Refinery Profits via Fine Management of Hydrogen Networks

Hydrogen network management is important to refineries. Various systematic management techniques have been developed to improve the efficiency of refinery hydrogen networks. However, existing methods all treat the hydrogen network separately. The tradeoff between hydrogen network cost and oil processing network benefit has not been explored in the hydrogen network management yet. A novel sensitivity analysis scheme is presented to take oil processing network into consideration. Oil processing unit which is sensitive to both oil processing networks and hydrogen networks is identified first. Then, sensitivity analysis of the unit around the operating point of oil processing networks and hydrogen networks is carried out. Finally, the overall optimal operating condition is obtained. An example of a real Chinese refinery demonstrates the effectiveness of the proposed analysis method.

A procedure for design of hydrogen networks with multiple contaminants

It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the design procedure, the precedence of processes is determined by the values of concentration potential of demands.The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to illustrate the effectiveness of the method. It is shown that the design procedure has clear engineering meaning.

Hydrogen Bond Networks' QSAR and Topologica Analysis of Konjac Glucomannan Chains

Based on the knot theory and researching of network structures of glucomannan molecules, the polysaccharides were analyzed. The link prediction analysis is to further reveal the interactions between polysaccharides, to elaborate QSAR of polysaccharides, and to analyze the network conformation relationships among polysaccharides. We made a classification for glucomannan molecules based on the related domestic and international theories, and investigated their network structures and application prospects. The knot theory and the link predictions not only simplify the glucomannan microscopic descriptions but also play a guiding role in predicting and regulating the structures.

Luminescence regulation of Sb^(3+)in 0D hybrid metal halides by hydrogen bond network for optical anti-counterfeiting

The Sb^(3+) doping strategy has been proven to be an effective way to regulate the band gap and improve the photophysical properties of organic-inorganic hybrid metal halides(OIHMHs).However,the emission of Sb^(3+) ions in OIHMHs is primarily confined to the low energy region,resulting in yellow or red emissions.To date,there are few reports about green emission of Sb^(3+)-doped OIHMHs.Here,we present a novel approach for regulating the luminescence of Sb^(3+) ions in 0D C_(10)H_(2)_(2)N_(6)InCl_(7)·H_(2)O via hydrogen bond network,in which water molecules act as agents for hydrogen bonding.Sb^(3+)-doped C_(10)H_(2)2N_(6)InCl_(7)·H_(2)O shows a broadband green emission peaking at 540 nm and a high photoluminescence quantum yield(PLQY)of 80%.It is found that the intense green emission stems from the radiative recombination of the self-trapped excitons(STEs).Upon removal of water molecules with heat,C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7) generates yellow emis-sion,attributed to the breaking of the hydrogen bond network and large structural distortions of excited state.Once water molecules are adsorbed by C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7),it can subsequently emit green light.This water-induced reversible emission switching is successfully used for optical security and information encryption.Our findings expand the under-standing of how the local coordination structure influences the photophysical mechanism in Sb^(3+)-doped metal halides and provide a novel method to control the STEs emission.

Modeling and Multi-objective Optimization of Refinery Hydrogen Network

The demand of hydrogen in oil refinery is increasing as market forces and environmental legislation, so hydrogen network management is becoming increasingly important in refineries. Most studies focused on single-objective optimization problem for the hydrogen network, but few account for the multi-objective optimization problem. This paper presents a novel approach for modeling and multi-objective optimization for hydrogen network in refineries. An improved multi-objective optimization model is proposed based on the concept of superstructure. The optimization includes minimization of operating cost and minimization of investment cost of equipment. The proposed methodology for the multi-objective optimization of hydrogen network takes into account flow rate constraints, pressure constraints, purity constraints, impurity constraints, payback period, etc. The method considers all the feasible connections and subjects this to mixed-integer nonlinear programming （MINLP）. A deterministic optimization method is applied to solve this multi-objective optimization problem. Finally, a real case study is intro-duced to illustrate the applicability of the approach.

Studies on Hydrogen Bonding Network Structures of Konjac Glucomannan

In this paper, the hydrogen bonding network models of konjac glucomannan （KGM） are predicted in the approach of molecular dynamics （MD）. These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O（6） and O（2） positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.

Pinch Location of the Hydrogen Network with Purification Reuse

In the hydrogen network with the minimum hydrogen utility flow rate,the pinch appears at the point with zero hydrogen surplus,while the hydrogen surpluses of all the other points are positive.In the hydrogen purity profiles,the pinch can only lie at the sink-tie-line intersecting the source purity profile.According to the alternative distribution of the negative and positive regions,the effect of the purification to the hydrogen surplus is analyzed.The results show that when the purification is applied,the pinch point will appear neither above the purification feed nor between the initial pinch point and the purification feed,no matter the purification feed lies above or below the initial pinch point.This is validated by two case studies.

Integration strategies of hydrogen network in a refinery based on operational optimization of hydrotreating units

Inferior crude oil and fuel oil upgrading lead to escalating increase of hydrogen consumption in refineries.It is imperative to reduce the hydrogen consumption for energy-saving operations of refineries.An integration strategy of hydrogen network and an operational optimization model of hydrotreating(HDT)units are proposed based on the characteristics of reaction kinetics of HDT units.By solving the proposed model,the operating conditions of HDT units are optimized,and the parameters of hydrogen sinks are determined by coupling hydrodesulfurization(HDS),hydrodenitrification(HDN)and aromatic hydrogenation(HDA)kinetics.An example case of a refinery with annual processing capacity of eight million tons is adopted to demonstrate the feasibility of the proposed optimization strategies and the model.Results show that HDS,HDN and HDA reactions are the major source of hydrogen consumption in the refinery.The total hydrogen consumption can be reduced by 18.9%by applying conventional hydrogen network optimization model.When the hydrogen network is optimized after the operational optimization of HDT units is performed,the hydrogen consumption is reduced by28.2%.When the benefit of the fuel gas recovery is further considered,the total annual cost of hydrogen network can be reduced by 3.21×10~7CNY·a^(-1),decreased by 11.9%.Therefore,the operational optimization of the HDT units in refineries should be imposed to determine the parameters of hydrogen sinks base on the characteristics of reaction kinetics of the hydrogenation processes before the optimization of the hydrogen network is performed through the source-sink matching methods.

Fuzzy optimization design of multicomponent refinery hydrogen network

Hydrogen and light hydrocarbon components are essential resources of the refinery.The optimization of the refinery hydrogen system and recovery of the light hydrocarbon components contained in the gas streams are key strategies to reduce the operating costs for sustainable development.Many research efforts have been focused on the optimization of single impurity hydrogen network,and the flowrates of the hydrogen sources and sinks are assumed to be constant.However,their flowrates vary along with the quality of crude oil and refinery processing plans.A general superstructure of multicomponent refinery hydrogen network is proposed,which considers four components,namely H_(2),H_(2)S,CH_(4) and C_(2+),as well as the flowrate variations of hydrogen source and hydrogen sink.The mathematical model based on the superstructure is developed with objective functions,including the minimization of total annualized cost and the maximization of overall satisfaction of the hydrogen network.Moreover,the model considers the removal of hydrogen sulfide and the recovery of light hydrocarbon components(i.e.,C_(2+))in the optimization.To verify the applicability of the proposed mathematical model,a simplified industrial case study with four scenarios is solved.The optimization results show that the economic benefit can be maximized by considering both the direct reuse of gas streams from high-pressure separator(HP gas stream)and from low-pressure separator(LP gas stream)and the recovery of the light hydrocarbon streams.The fuzzy optimization method can be used to guide the optimal design of the refinery hydrogen system with multi-period variable flowrates.

A Perfect Three-dimensional Hydrogen Bonding Network within Hydroxonium Hexa-aqua-magnesium(Ⅱ) Trichloride

Hydrothermal reaction of MgCl2 and ethyl tetrazolate-5-carboxylate at 160 ℃unexpectedly yielded compound {（H3O）[Mg（H2O）6]Cl3} （1）. The result of X-ray diffraction analysis indicates that 1 crystallizes in the monoclinic system, space group C2/c with a = 9.2896（3）, b = 9.5570（4）, c = 13.3169（5） A, β = 90.1221（12）°, V= 1182.28（8） A3, Z = 4, Mr = 257.78, Dc = 1.448 g/cm3, μ = 0.824 mm^-1, F（000） = 536, R = 0.0265 and wR - 0.0706. 1 is composed of one hexa-aqua-magnesium（Ⅱ） ion, one hydroxonium ion, and three chlorine anions. These three components weave a perfect three-dimensional （3D） （4,4,6,12）-connected hydrogen bonding network within 1.

Stability of the Konjac Glucomannan Topological Chain Based on Quantum Spin Model

In this paper we investigated the stability of konjac glucomnnan（KGM） chain hydrogen networks based on the quantum spin model. Dissipative particle dynamics method was applied in the structure simulation of KGM. The results reveled that acetyl residues of KGM were bonded with water molecules in aqueous solutions. Increasing the hydrogen bond formation decreases the energy in acetyl system. The expect-valuation of the thermal state with respect to the Hamiltonian is negative. Hence, the total energy of konjac glucomnnan chain with the acetyl groups decreases, which indicates the increasing stability of konjac glucomnnan chain. Our approach could provide a new insight into the investigation on the stability of konjac glucomnnan chain.

Hydrothermal Synthesis and X-ray Characterization of Silver(I) Complex:Diacetylthiocarbamide Silver(I) Nitrate, [Ag(CH_3CONHC(S)NH_2)_2](NO_3)

The title compound [Ag(CH3CONHC(S)NH2)2](NO3) has been prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. It crystallizes in mo-noclinic, space group P21/c with Mr = 406.20 (C6H12Ag N5O5S2), a = 12.0680(6), b = 6.8056(5), c = 18.0173(1) ? b = 111.383(4), V = 1377.9(2) 3, Z = 4, Dc = 1.958 g/cm3 , F(000) = 808, = 1.789 mm-1, R = 0.0361 and wR = 0.1015. Of 4185 reflections ((2)max = 55.00?, 3147 were unique (Rint = 0.0174) and 2820 with I > 2(I) were used to solve the structure. The silver(I) atom adopts V-shape geometry with the AgS bond distance of 2.4271(7) and 2.7229(9) , respectively. Seven atoms of one acetylthiocarbamide ligand are coplanar, while only four atoms of another acetylthio-carbamide ligand are fairly planar. The [Ag(CH3CONHC(S)NH2)2]+ cation and nitrate anion NO3- are connected by hydrogen bonds to form a three dimensional hydrogen bonding network..

High-Performance Recyclable Furan-based Epoxy Resin and Its Carbon Fiber Composites with Dense Hydrogen Bonding

The emerging biomass-based epoxy vitrimers hold great potential to fulfill the requirements for sustainable development of society.Since the existence of dynamic chemical bonds in vitrimers often reduces both the thermal and mechanical properties of epoxy resins, it is challenging to produce recyclable epoxy vitrimers with both excellent mechanical properties and good thermal stability. Herein, a monomer 4-(((5-(hydroxymethyl)furan-2-yl)methylene)amino)phenol(FCN) containing furan ring with potential to form high density of hydrogen bonding among repeating units is designed and copolymerized with glycerol triglycidyl ether to yield epoxy resin(FCN-GTE), which intrinsically has dual hydrogen bond networks, dynamic imine structure and resultant high performance. Importantly, as compared to the BPA-GTE, the FCN-GTE exhibits significantly improved mechanical properties owing to the increased density of hydrogen bond network and physical crosslinking interaction. Furthermore, density functional theory(DFT) calculation and in situ FTIR analysis is conducted to decipher the formation mechanism of hydrogen bond network. In addition, the FCN-GTE possesses superior UV shielding, chemical degradation, and recyclability because of the existence of abundant imine bonds. Notably, the FCN-GTE-based carbon fiber composites could be completely recycled in an amine solution.This study provides a facile strategy for synthesizing recyclable biomass-based high-performance epoxy vitrimers and carbon fiber composites.

Supramolecular Network Obtained from the Interaction of Dihydrophosphate Anions and Thiourea-based Receptors

Two crystals of receptor 1, C（42）H（52）N（10）O4S2（anthracene-9,10-dicarbaldehyde bis-（phenyl-semithiocarbazone）） and-1-H2PO4, C（68）H（114）N（10）O（10）P2S2 were obtained at room temperature successfully, and their structures were characterized by X-ray crystallography diffraction. X-ray diffraction reveals that, receptor 1 crystallizes in monoclinic, space group P21/c, with a = 9.487（3）,b = 20.674（6）, c = 11.821（4）A, β = 113.416（8）o, Mr = 825.06, V = 2127.5（12） A^3, Z = 2, Dc = 1.288g/cm^3, μ = 0.18 mm^-1, F（000） = 876, MoK α radiation（λ = 0.71073 A）, the final R = 0.0472 and wR = 0.0930. A total of 3758 unique reflections were collected, of which 3313 with I 〉 2σ（I） were observed. Compound 1-H2PO4^-crystallizes in triclinic, space group P21/n, with a = 8.767（1）, b =13.6190（15）, c = 16.615（2） ？, α = 98.727（14）, β = 103.061（14）, γ = 91.382（16）°, Mr = 1357.75, V =1906.6（4） A^3, Z = 1, Dc = 1.183 g/cm^3, μ = 0.17 mm-（-1）, F（000） = 734, MoK α radiation（λ = 0.71073？）, the final R = 0.0769 and wR = 0.1884. A total of 6699 unique reflections were collected, of which 2989 with I 〉 2σ（I） were observed. As it was observed in the crystal structure of 1-H2PO4^-, 1bound H2PO4^-at a 1：2 ratio by intermolecular interaction of N-H···O hydrogen bond obviously.Another interesting feature was that H2PO4--groups assembled chains themselves via intramolecular hydrogen bond O-H···O and connected the 1 molecules together through the interaction of H-bonds,which improved the planarity of 1 and increased the stability of the entire structure.

An Interfacial Gel Electrode Patch with Tunable Hydrogen Bond Network for Electromyographic Sensing and Discrimination

The sensitivity and fidelity of surface electromyography(sEMG)signal monitoring is critical for muscle status and fatigue assessment,prosthetic control,and gesture recognition.However,the incompatible skin-electrode interface and complex electrophysiological environment restrict the sensitive acquisition and accurate analysis of sEMG signals.Focused on the impedance of the skin-electrode interface issue,we developed an interfacial gel electrode patch with a tunable hydrogen bond network to simultaneously achieve a conformal interface,suitable adhesion,and high conductivity for sEMG signal monitoring.By exploiting hydroxyethylidene diphosphonic acid(HEDP)and 2-hydroxyphosphono-acetic acid(HPAA)as hydrogen bonding regulators were introduced into the polyvinyl alcohol(PVA)-based hydrogel network to regulate the hydrogen bond cross-linking network.As a result,the balance of elastic modulus,adhesion,and electrical conductivity of PVA-HEDP-HPAA(PHH)hydrogel are achieved.The reliable electrodeskin interface is manipulated to achieve conformal contact by matching the elastic modulus,reducing the gap of electrode-skin interface by adhesion,and promoting ion and electron conduction by electrical conductivity.The PHH electrode patches exhibit a lower interfacial impedance(12.56 kΩ)and a signal-to-noise ratio of 38.09±1.28 dB for accurate analysis of muscle strength and evaluation of the fatigue state.With the assistance of the artificial neural network algorithm,seven gestures can be recognized with 100%prediction accuracy.The interfacial gel electrode patch contributes a bio-matching electrophysiological platform for prosthetic control,human–machine interaction,and clinical or athletic auxiliary monitoring.

Synthesis and Crystal Structure of 2-Chloromethyl-1H-benzimidazole Nitrate, [ClCH_2(C_7H_6N_2)]NO_3

The title compound [ClCH2(C7H6N2)]NO3 has been prepared and characterized by elemental analysis and X-ray studies. It crystallizes in the monoclinic system, space group P21/n with a = 7.4189(3), b =15.3064(6), c = 9.2657(3) ? b = 102.449(2)? C8H8ClN3O3, Mr = 229.62, V = 1027.44(7) 3, Z = 4, Dc = 1.484 g/cm3, F(000) = 472, = 0.363 mm-1, R = 0.0671 and wR = 0.1546. The crystal structure consists of discrete 2-chloromethyl-1H-benzimidazole cations and NO3- anions. The benzimidazole ring with the conjunction carbon atom C(1) is fairly planar, with the deviation from the least plane through the ring atoms is smaller than 0.010(3) ? The analytical results of crystal structure show that three different non-covalent interactions in the compound, NH…O intermolecular hydrogen bonds, CH…O interaction and p-p stacking interaction, play an important role in the crystal packing.

Crystal Structure and Spectroscopic Studies of Diphenylcarbazide Acetonitrile Solvate,(PhNHNH)_2C=O·CH_3CN

The title compound (PhNHNH)2C=OCH3CN has been prepared and characterized by elemental analysis and IR spectrum studies. The single-crystal X-ray structure determination of the title compound was carried out. It crystallizes in the monoclinic system, space group P21/n with a = 5.7818(2), b = 15.320(1), c = 17.469(1) ? b = 97.476(1)? V = 1534.2(1) 3, Mr = 283.34 (C15H17N5O), Z = 4, Dc = 1.227 g/cm3 , F(000) = 600, ?= 0.082 mm-1, R = 0.0561 and wR = 0.1538. The total reflections were 8214 and the independent ones were 2624 (Rint = 0.0559), of which 1756 were observed with I > 2s(I). The torsion angles of the important groups (C(6)N(1) N(2)C(7) and C(7)N(3)N(4)C(8)) are 68.3(3) and 93.3(3), respectively. In the crystal lattice, the molecules form a network structure through hydrogen bonds. The crystal structure is stabilized by NH…N and NH…O hydrogen bonds. FT-IR spectra clearly show there exist acetonitrile molecules in the crystal lattice.

Synthesis and Crystal Structure of α-(1,2,4-Triazol-1H-yl)-ρ-chloro Acetophenone, [ClC_6H_4COCH_2(C_2H_2N_3)]

The title compound [ClC6H4COCH2(C2H2N3)] has been prepared and characterized by elemental analysis, IR spectrum and X-ray studies. It crystallizes in the monoclinic system, space group P21/c with Mr = 221.64 (C10H8ClN3O), a = 13.420(3), b = 9.720(2), c = 7.900(2) ? b = 92.00(3)? V = 1029.9(4) 3, Z = 4, Dc = 1.429 g/cm3, F(000) = 456, m = 0.345 mm-1, R = 0.0435 and wR=0.0894. The total reflections were 1949 and the independent ones were 1805 (Rint=0.0340), of which 800 were observed with I > 2s(I). The crystal structure consists of a-(1,2,4-triazol-1H- yl)-r-chloro-acetophenone. The existence of p conjugated systems in the molecule affects partly the bond lengths. The triazole and phenyl rings form the dihedral angle of 77.34. The molecules of the title compound connect to each other through extensive hydrogen bonds to form a two-dimensional structure. Elemental analysis and IR spectra are in good agreement with the structure data.