Energy and exergy optimization of oxidative steam reforming of acetone–butanol–ethanol–water mixture as a renewable source for H2 production via thermodynamic modeling

Acetone–butanol–ethanol–water mixture is obtained by fermentation of biomass namely, corncob, wheat straw, sugarbeets, sugarcane, etc. For using the individual components, one alternative is to separate the mixture by distillation, which is costly and energy intensive operation. This paper proposes its other use in available conditions to produce hydrogen fuel by oxidative steam reforming process. For the proposed process, thermodynamic equilibrium modeling has been performed by using non-stoichiometric approach of Gibbs free energy minimization. The compositions of acetone, butanol and ethanol in mixture are 0.33:0.52:0.15 on molar basis. The influence of pressure (1–10 atm), temperature (573–1473 K), steam to ABE mixture molar feed ratio (F ABE = 5.5–8.5), and oxygen to ABE mixture molar feed ratio (F OABE = 0.25–1) have been tested by simulations on the yield of products (at equilibrium) namely, H2, CH4, CO2, CO, and carbon as solid. The optimum conditions for maximum production of desired H2, minimization of undesired CH4, and elimination of carbon (solid) formation are T = 973 K, P = 1 atm, F ABE = 8.5, and F OABE = 0.25. Under same operating conditions, the maximum generation of H2 is 7.51 on molar basis with negligible carbon formation. The total energy requirement for the process (295.73 kJ/mol), the energy required/mol of hydrogen (39.37 kJ), and thermal efficiency (68.09%) of the reformer have been obtained at same operating conditions. The exergy analysis has also been investigated to measure the work potential of the energy implied in the reforming process.

Tailoring Intrinsic Properties of Polyaniline by Functionalization with Phosphonic Groups

Phosphonated polyanilines were synthesized by copolymerization of aniline (ANI) with both 2- and 4-aminophenylphosphonic acids (APPA). The material composition and the final properties of the copolymers can be easily tailored by controlling the monomers ANI/APPA molar feed ratio. An important influence on the reactivity of monomers has been found with the substituent position in the ring, leading to differences in the properties and size of blocks of each monomer in the polymer. As expected, while 2APPA shows more similarities to ANI, 4APPA is much less reactive. Phosphorus loading of ~5 at% was achieved in the poly(aniline-co-2-aminophenylphosphonic acid) (PANI2APPA) with a 50/50 molar feed ratio. All the resulting copolymers were characterized by different techniques. Experimental results and density functional theory (DFT) computational calculations suggest that the presence of phosphonic groups in the polymeric chain gives rise to inter- and intra-chain interactions, as well as important steric effects, which induce a slight twist in the substituted PANI structure. Therefore, the physicochemical, electrical, and electrochemical properties are modified and can be suitably controlled.

Effect of Composition on the Crystallization, Water Absorption, and Biodegradation of Poly(ε-caprolactam-co-ε-caprolactone) Copolymers

Poly(ester amide)s have aroused extensive research interest due to the combination of the degradability of polyester and the higher mechanical properties of polyamide. In this work, a series of poly(ε-caprolactam-co-ε-caprolactone) (P(CLA-co-CLO)) copolymers with different compositions were synthesized by anionic copolymerization. The structure, crystallization behavior, water absorption, and biodegradation behavior of these copolymers were investigated by means of nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical micrographs (POM). The results indicated that the composition of P(CLA-co-CLO) copolymers can be adjusted by the molar feed ratio. The PCL blocks decreased the crystallization rate of PA6 blocks but had little effect on the melting behavior of PA6, while the crystallized PA6 acted as a heterogeneous nucleating agent and greatly improved the crystallization rate of PCL. Moreover, the introduction of PCL blocks greatly reduced the water absorption of P(CLA-co-CLO) copolymers and endow them a certain degree of degradability.

Methane and Ethane Steam Reforming over MgAl2O4-Supported Rh and Ir Catalysts: Catalytic Implications for Natural Gas Reforming Application

Solar concentrators employed in conjunction with highly efficient micro- and meso-channel reactors offer the potential for cost-effective upgrading of the energy content of natural gas, providing a near-term path towards a future solar-fuel economy with reduced carbon dioxide emissions. To fully exploit the heat and mass transfer advantages offered by micro- and meso-channel reactors, highly active and stable natural gas steam reforming catalysts are required. In this paper, we report the catalytic performance of MgAl2O4-supported Rh (5 wt.%), Ir (5 wt.%), and Ni (15 wt.%) catalysts used for steam reforming of natural gas. Both Rh- and Ir-based catalysts are known to be more active and durable than conventional Ni-based formulations, and recently Ir has been reported to be more active than Rh for methane steam reforming on a turnover basis. Thus, the effectiveness of all three metals to perform natural gas steam reforming was evaluated in this study. Here, the Rh- and Ir-supported catalysts both exhibited higher activity than Ni for steam methane reforming. However, using simulated natural gas feedstock (94.5% methane, 4.0% ethane, 1.0% propane, and 0.5% butane), the Ir catalyst was the least active (on a turnover basis) for steam reforming of higher hydrocarbons (C2+) contained in the feedstock when operated at <750 °C. To further investigate the role of higher hydrocarbons, we used an ethane feed and found that hydrogenolysis precedes the steam reforming reaction and that C–C bond scission over Ir is kinetically slow compared to Rh. Catalyst durability studies revealed the Rh catalyst to be stable under steam methane reforming conditions, as evidenced by two 100-hour duration experiments performed at 850 and 900 °C (steam to carbon [S/C] molar feed ratio = 2.0 mol). However, with the natural gas simulant feed, the Rh catalyst exhibited catalyst deactivation, which we attribute to coking deposits derived from higher hydrocarbons contained in the feedstock. Increasing the S/C molar feed ratio from 1.5 to 2.0 reduced the deactivation rate and stable catalytic performance was demonstrated for 120 h when operated at 850 °C. However, catalytic deactivation was observed when operating at 900 °C. While improvements in steam reforming performance can be achieved through choice of catalyst composition, this study also highlights the importance of considering the effect of higher hydrocarbons contained in natural gas, operating conditions (e.g., temperature, S/C feed ratio), and their effect on catalyst stability. The results of this study conclude that a Rh-supported catalyst was developed that enables very high activities and excellent catalytic stability for both the steam reforming of methane and other higher hydrocarbons contained in natural gas, and under conditions of operation that are amendable to solar thermochemical operations.

Synthesis and characterization of electrically conducting copolymers of poly(aniline-co-o-iodoaniline)

Functionalized copolymers of poly(aniline-co-o-iodoaniline) have been synthesized by the chemical oxidative polymerization method by using o-iodoaniline (o-IA) and aniline (AN) as monomer units by changing their molar feed ratio in acid aqueous medium. The physical properties viz; solubility, electrical conductivity have been studied to characterize them. The copolymers possess better solubility than unsubstituted homopolymer in organic solvent such as N -methyl-2-pyrrodinone (NMP). The conductivity of the pressed pellets of as-synthesized copolymers depends upon the content of o-IA in the polyaniline (PANI). The structural confirmation of the copolymer has been explained by Fourier transform infrared spectroscopy study which suggest that AN and o-IA units are uniformly distributed along the polymer chain and thus, the physical properties of copolymers may possibly be tailored by varying the molar feed ratio in copolymerization reactions. The conductivity of the copolymer decreases upon increasing the o-IA content in molar feed, because the introduction of –I- as a functional group reduces the extent of conjugation of the polymer chain.

Synthesis of a Biodegradable Material Poly(lactic acid-co-melamine) via Direct Melt Polycondensation

Directly starting fromD,L-lactic acid (LA) and melamine (MA), novel star-shaped biodegradable material poly (lactic acid-co-melamine) [P(LA-co-MA)] as a kind of potential flame retardant is synthesized via melt polycondensation. When the molar feed ration(LA)/n(MA) is 60/1, the optimal synthetic conditions are discussed. After the prepolymerization at 140 °C for 8 h, using 0.4wt% stannous chloride as the catalyst, the melt copolymerization at 160 °C for 8 h gives the copolymer with the biggest intrinsic viscosity 0.87 dLg-1.

Reaction Mechanism on the Modification of PLA by Melamine via DMP

When poly (lactic acid-co-melamine) [P(LA-co-MA)] is synthesized via direct melt polycondensation (DMP), with the more MA in the feed content, the copolymer with a three-MA-core structure linked by the ether bond is formed. Increasing the molar feed ration(LA)/n(MA), the structure of the copolymers is gradually changed from multi-core structure into SPLA structure only containing one MA core, and a peak value of Mwexists as expected. The aromatic cores with different functional groups have an important influence on the Mwpeak value, and the internal factors are the conjugate effect and the nucleophilicity caused by the different functional groups themselves.

Catalytic Performance of Fe-Mn/SiO2Nanocatalysts for CO Hydrogenation

A series ofx(Fe, Mn)/SiO2nanocatalysts (x=5, 10, 15, 20, 25, and 30 wt.%) were prepared by sol-gel method and studied for the light olefins production from synthesis gas. It was found that the catalyst containing 20 wt.% (Fe, Mn)/SiO2is an optimal nano catalyst for production of C2–C4olefins. Effects of sulfur treatment on the catalyst performance of optimal catalyst have been studied by espousing different volume fractions of H2S in a fixed bed stainless steel reactor. The results show that the catalyst treated with 6 v% of H2S had high catalytic performance for C2–C4light olefins production. The best operational conditions were H2/CO = 3/2 molar feed ratio at 260°C and GHSV = 1100 h−1under 1 bar total pressure. Characterization of catalysts was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and surface area measurements.

Synthesis and properties of novel poly(ether ether ketone) copolymers with (3,5-ditrifluoromethyl)phenyl and (4-phenoxy)phenyl side groups

A new nonfluorinated bisphenol monomer 2-(4-phenoxyphenyl)-1,4-diphenol was prepared via a four-step synthesis process. A series of poly(ether ether ketone) copolymers (6FPOP-PEEKs) were derived from 4,4′-difluorobenzophenone via a nucleophilic aromatic substitution polycondensation with various molar feed ratios of bisphenol monomer, 2-(4-phenoxyphenyl)-1,4-diphenol to (3,5-ditrifluoromethyl)phenylhydroquinone. The molecular weights ( Mn values), polydispersities and Tg values of 6FPOP-PEEKs increase as the molar feed ratio of 6FPH/(6FPH+POPH) increases. These 6FPOP-PEEKs show very high thermal stability. At a wavelength of 1550 nm, the refractive indices of the 6FPOP-PEEKs films are in the range of 1.5992–1.6396 and birefringences are in the range of 0.0034–0.0043. The near-infrared spectra show that the 6FPOP-PEEK films have small light absorption at the telecommunication wavelengths of 1300 and 1550 nm.

Research on the Modification of Poly(L-Lactic Acid) by Glucose via Direct Melt Polycondensation

Directly using L-lactic acid (L-LA) and glucose (Glu) as the starting materials, novel biodegradable material poly(L-lactic acid-co-glucose) [P(L-LA-co-Glu)] was synthesized via direct melt polycondensation. The copolymers P(L-LA-co-Glu)s at different molar feed ratios were characterized by FTIR,1H-NMR, GPC, DSC and XRD. All poly(L-lactic acid) modified by Glu was partly crystalline. And their Mw, Tm, and crystallinity basically increased with the increase of the molar feed ratio n(L-LA) : n(Glu). When n(Glu) : n(L-LA) was 1 : 750, the biggest Mw was 5900 Da, and all Mwcould meet the requirement for drug delivery application.