Yongrong Yang

Sustainability performance evaluation in industry by composite sustainability index

The growing importance of sustainable development as a policy objective has initiated a debate about those suitable frameworks and tools useful for policy makers when making a sustainable decision. Composite indicators (CIs) aggregate multidimensional issues into one index, thus providing comprehensive information. However, it is frequently argued that CIs are too subjective, as their results undesirably depend on the normalization method, a specific weighting scheme, and the aggregation method of sub-indicators. This article applies different combinations of normalization, weighting, and aggregation methods for the assessment of an industrial case study, with the aim of determining the best scheme for constructing CIs. The applied methodology gradually aggregates sustainable development indicators into sustainability sub-indices and, finally, to a composite sustainability index. The normalization methods included in this analysis are: minimum–maximum, distance to a reference, and the percentages of annual differences over consecutive years. Equal weightings, the ‘benefit of the doubt’ approach, and budget allocation process were used for determining the weights of individual indicators and sustainability sub-indices. The linear, geometric, and non-compensatory multi-criteria approaches (NCMCs) were used as aggregation methods. The NCMC is modified to fit the two-level aggregation, then to sub-indices, and finally to a composite sustainable index. Also, a penalty criterion is introduced into the evaluation process with the aim of motivating the company to move towards sustainable development. The results are analyzed by variance-based sensitivity analysis. According to the results the recommended scheme for CIs’ construction is: distance to a reference–benefit of the doubt–linear aggregation.

Design Energy Efficient Water Utilization Systems Allowing Operation Split

Abstract This article deals with the design of energy efficient water utilization systems allowing operation split. Practical features such as operating flexibility and capital cost have made the number of sub operations an important parameter of the problem. By treating the direct and indirect heat transfers separately, target freshwater and energy consumption as well as the operation split conditions are first obtained. Subsequently, a mixed integer non-linear programming (MINLP) model is established for the design of water network and the heat exchanger network (HEN). The proposed systematic approach is limited to a single contaminant. Example from literature is used to illustrate the applicability of the approach.

Catalytic performance of AuIII supported on SiO2 modified activated carbon

Silica was deposited onto activated carbon through TEOS hydrolysis and this composite was used as a support for the Au catalyst in acetylene hydrochlorination. Silica content and the catalyst synthesis process were both optimized. It was found that 1Au/5SiO2/AC showed improved stability, while being as active as 1Au/AC. Thermogravimetric analysis (TGA) quantitatively revealed the synchronism of TEOS hydrolysis and Au deposition, which was believed to be the linchpin in 1Au/5SiO2/AC synthesis. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrated that amorphous silica dispersed on the carbon surface uniformly as spherical particles. Silica deposition brought down the surface area of the catalyst while leading to better distribution of gold nanoparticles. Higher gold distribution degree guaranteed the catalytic activity of 1Au/5SiO2/AC despite surface area loss. A higher level of resistance to acetylene, excellent surface property stability and less carbonaceous deposition were determined as the origin of the improved stability of 1Au/5SiO2/AC.

Efficient Au 0/C catalyst synthesized by a new method for acetylene hydrochlorination

A new impregnation method, involving a mixture of solvents and a vacuum drying process, was used to prepare a gold catalyst (MIV-1Au/C1) for acetylene hydrochlorination. It was found that MIV-1Au/C1 was twice as active as the catalyst prepared through the traditional method (PI-1Au/C1). The new method is green, mild and simple. Moreover, it appears to be controllable by tuning solvent and temperature. Excellent Au dispersion in MIV-1Au/C1 was revealed by transmission electron microscopy (TEM). In addition, X-ray photoelectron spectroscopy (XPS) profiles proved that Au0 was the only active species of MIV-1Au/C1 at the initial/highest point of testing. Further XPS results showed that Au0 could be oxidized to Au3+ during the reaction along with the deactivation of MIV-1Au/C1. Thus, Au0 appeared to be preferred for the catalytic route. Our findings demonstrate that this new method has potential as a catalyst for acetylene hydrochlorination. Moreover, this study highlighted the importance of Au0 in this field.

Improvement of performance of a Au–Cu/AC catalyst using thiol for acetylene hydrochlorination reaction

In order to overcome problems of Au–Cu bimetallic catalysts for acetylene hydrochlorination reaction such as instability, Au–Cu–SH/AC catalysts were prepared through the introduction of thiol and tested to examine their activity and stability. It was found that performances of Au–Cu–SH/AC catalysts were quite excellent, with significantly higher catalytic activity and better stability than performances of Au/AC and Au–Cu/AC catalysts. The contents of Cu and thiol additives were also optimized and the optimum molar ratio of Au/Cu/SH was 1 : 1 : 10. Catalyst samples were characterized by scanning electron microscopy (SEM), nitrogen adsorption/desorption (BET), X-ray diffraction (XRD), transmission electronic microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). It was demonstrated that the Au–Cu–SH/AC catalysts were Au0-based catalysts, due to thiol reducing Au3+ to Au0 species during the preparation process. Au0 species exhibited better catalytic activity than Au3+ species for acetylene hydrochlorination, according to the comparison with the composition of active species in different samples through XPS. Furthermore, the sulfhydryl of thiol could bond to the surface of gold nanoparticles (Au NPs). It helped in mitigating the oxidation of Au0 by HCl, protecting Au NPs from structure damage, stabilizing Au NPs in a nearly constant particle size and keeping a more active structure in the reaction environment. Thus, improved dispersity of active species and protection of the active structure of the Au NPs resulted in the better catalytic activity and stability of Au–Cu–SH/AC.

Computational fluid dynamics simulations of interphase heat transfer in a bubbling fluidized bed

Numerical simulations based on the Eulerian-Eulerian approach have been performed in the study of interphase heat transfer in a gas solid fluidized bed. The kinetic theory of granular flow (KTGF) has been used to describe the solid phase rheology. An assessment of drag models in the prediction of heat transfer coefficients shows that no major difference is observed in the choice of the drag model used. Fluctuations of the interphase heat transfer coefficient have been found to be closely related to the bubble motion in the bed. Effects of the wall boundary condition, inlet gas velocity, initial bed height and particle size on the predicted heat transfer coefficient have also been investigated. Typical temperature profiles in the bed show that thermal saturation is attained instantaneously close to the gas distributor. Simulated results of the coefficients are in fair agreement with those reported in literature.

Investigation of reinforcement of the modified carbon black from wasted tires by nuclear magnetic resonance

Pyrolysis has the potential of transforming waste into recyclable products. Pyrolytie carbon black (PCB) is one of the most important products from the pyrolysis of used tires. Techniques for surface modifications of PCB have been developed. One of the most significant applications for modified PCB is to reinforce the rubber matrix to obtain high added values. The transverse relaxation and the chain dynamics of vulcanized rubber networks with PCB and modified PCB were studied and compared with those of the commercial carbon blacks using selective 1H transverse relaxation (T2) experiments and dipolar correlation effect (DCE) experiments on the stimulated echo. Demineralization and coupling agent modification not only intensified the interactions between the modified PCB and the neighboring polyisoprene chains, but also increased the chemical cross-link density of the vulcanized rubber with modified PCB. The mechanical testing of the rubbers with different kinds of carbon blacks showed that the maximum strain of the rubber with modified PCB was improved greatly. The mechanical testing results confirmed the conclusion obtained by nuclear magnetic resonance (NMR). PCB modified by the demineralization and NDZ-105 titanate coupling agent could be used to replace the commercial semi-reinforcing carbon black.

Promotional effect of Ti doping on the ketonization of acetic acid over a CeO2 catalyst

A series of Ce1−xTixO2−δ mixed oxide catalysts were synthesized using a homogeneous precipitation method and characterized, and then these catalysts were applied to convert acetic acid to acetone using a gas-phase ketonization reaction. Ti-doped Ce1−xTixO2−δ catalysts (x = 0.1–0.5) exhibited much better ketonization performance than their parent catalysts of CeO2 and TiO2, and such Ti-doping-induced catalysis improvement is attributed to the formation of a Ce–O–Ti structure depending on the Ti content. Among the different Ce1−xTixO2−δ catalysts, the Ce0.7Ti0.3O2−δ catalyst calcinated at 500 °C showed the best catalysis activity and high stability. A combination of techniques (i.e. TEM, FTIR, H2-TPR, NH3/CO2-TPD and XPS) further revealed that the formation of the Ce–O–Ti structure modified the surface acid–base properties and thus enhanced the redox properties. Moreover, the introduction of Ti into CeO2 also increased the number of oxygen vacancies on the catalysts’ surface that favored the ketonization of acid molecules. This work provides valuable insights into the design of highly efficient CeO2-based catalysts for acid removal in the upgrading process of bio-oil.

Exploring the effects of phenolic compounds on bis(imino)pyridine iron-catalyzed ethylene oligomerization

In order to reduce the simultaneous production of insoluble polymers during the bis(imino)pyridine (BIP) iron-catalyzed ethylene oligomerization, a series of phenolic compounds were introduced as modifiers. It was found that the polymer share in the total products would be largely reduced with the increasing dosage of the phenols and the enlargement of para-substituent size from methyl to tert-butyl. Further 1H NMR studies showed that the phenols could provide methylaluminoxane (MAO) profound structural modifications, giving rise to larger MAO aggregates and decoration of phenoxy groups on its surface. This would thus facilitate the active ion pair separation, leading the phenols to become effective polymer-retarding modifiers. Starting from the reaction between 4-tert-butylphenol, AlMe3 and water, a novel phenoxy-aluminoxane could be prepared. Its combination with AlMe3 enabled the catalyst activation, and gave us a further verification about the important role of phenoxy groups on the MAO surface. Furthermore, the introduction of electron-withdrawing groups would improve the reactivity of the –OH group, promoting the interaction between the phenols and MAO. A series of para-halogen substituted phenols were thus developed. With the relatively large size of the bromo group and the highest reactivity of the –OH group, 4-bromophenol was proved to be the most efficient polymer-retarding modifier among the studied phenols in this work. An almost polymer-free ethylene oligomerization could be achieved by this strategy without altering the mono ortho-methyl substituted BIP ligand.

A STUDY OF ULTRASONIC RADIATION DISSIPATION IN POWDER PROCESSING SYSTEM

A model of ultrasonic radiation damping is presented to describe the dissipation of ultrasonic vibration energy in a solid processing system on the basis of vibration damping theory. Four kinds of polyethylene particles, with diameters varying from 0.15 to 0.85 mm and bulk densities varying from 499.6 to 252.5 kg·m−3, are put in a Plexiglas storage bin inserted with a Plexiglas bar, as powder material. Ultrasonic energies absorbed by these kinds of particles were detected by receivers at different levels. The results show that when distance between receiver and source of ultrasonic vibration is lengthened, the AE energy absorption increases, and it also increases when the bulk density of powder material is increased. It is also found that the ultrasonic vibration energy dissipates much more along the inserted bar than along the wall of a storage bin, because the inserted bar has greater radiation area. The results of experiments are accurately predicted by the radiation damping model presented in this article with a fairly good accuracy. Furthermore, a method of level gauging is developed to meet the requirements of different applications, such as online measurement of the particle material, to replace other level gauging methods.