Hydrodenitrogenation of isoquinoline

To determine the formation and reactivity of addition compounds produced during hydrodenitrogenation (HDN), we investigated the HDN of isoquinoline for a sulfided Ni–Mo/Al₂O₃ catalyst operated under a hydrogen pressure of 12 MPa (cold charge) in the temperature range 300–375°C. The reaction products were classified into five groups of compounds:

1. hydrogenated derivatives of isoquinoline (tetrahydroisoquinolines, decahydroisoquinolines, and their isomers);

2. nitrogen-containing ring-opened products (1-amino-2-(2-methylphenyl)ethane and 1-amino-1-(2-ethylphenyl)methane);

3. denitrogenated products (1-ethyl-2-methylbenzene, 1-ethyl-2-methylcyclohexane, and their isomers);

4. addition products (hydrocarbons with molecular weights of 238, 244, and 250 and nitrogen-containing compounds with molecular weights of 249, 251, and 257); and

5. cracked products (toluene, ethylbenzene, dimethylbenzenes, and their hydrogenated derivatives).

Most of the nitrogen-containing addition compounds appear to be substituted on the nitrogen atom. The HDN of isoquinoline was more than 10 times faster than the HDN of quinoline, whereas the hydrogenation of isoquinoline was difficult compared to the hydrogenation of quinoline. The reaction network for the HDN of isoquinoline is also presented.     

Low-temperature methanol synthesis from carbon dioxide and hydrogen via formic ester

A new route of methanol synthesis, at 443 K and under pressurized conditions, from carbon dioxide and hydrogen through formic ester was investigated, by using Cu-based catalysts. This one-pot reaction consisted of three steps:

1. formic acid synthesis from CO₂ and H₂,

2. esterification of formic acid by ethanol to ethyl formate, and

3. hydrogenolysis of ethyl formate to methanol and ethanol.

Sea water desalination by reverse osmosis in chigasaki laboratory

For the purpose of constructing a reverse osmosis [RO) sea water desalination plant of 800 m³/day capacity, a series of tests on the following themes have been carried out in the Chigasaki Laboratory:

1. Performance and durability of 8B modules made in Japan

2. Simplification of pretreatment system

3. Establishment of energy recovery system.

Domestic modules showed good and stable performance during long term operation, and water recovery ratio of these modules have been raised to 40%.

In-line coagulation and filtration system has been established for the pretreatment of feed sea water, instead of coagulation, sedimentation and filtration system.

The energy recovery equipment is consisted of a high-pressure pump, a motor and a hydraulic turbine on a common base. Recovered energy from pressurized brine is used for the auxiliary motive power of the high-pressure pump. The experimental data show that about 20% of required power for the pump was recovered.     

Solar multistage flash evaporation (smsf) as a solar energy application on desalination processes

The application of solar energy on desalination constitutes one of the activities of the research and development program of digases. Within this philosophy a project is being developed in cooperation with the Federal Republic of Germany. The objective of the project is to test and prove the feasibility of the solar energy utilization as the source of the thermal energy required for a multistage flash evaporation plant.

The plant is composed of three systems:

1. Desalination system. Multistage flash evaporation plant with 10m³/d production capacity, 5.0 in performance ratio and 10 stages.

2. Solar energy captation. Composed of one low temperature subsystem of double pipe flat collectors with 670m² of effective captation surface, and a high temperature subsystem composed of parabolic concentrators with 320m² of captation surface.

3. Storage of energy. System designed with such capacity which allows continuous operation of desalination unit.

The poject is separated into two phases. The first includes the design manufacturing and tests for the three systems. The second phase comprises the installation and integration of the systems which compose the plant, the start-up operation and evaluation of plant performance.

At the present time, the first phase of the project is under development and it is expected to finish it at the end of June. The second phase will start in August with system start-up scheduled for the end of October.     

Two detailed case studies of large Libyan desalination plants and their influence on development

Two large Libyan desalination plants are studied :

1. The Ganzour (Tripoli West) MSF plant with two units, each having a rated distillate output of 11,250 m³/day at full load, the distilla- te purity being 25 ppm. The reliability tests on this plant are just beginning and consequen- tly we shall stress on the erection problems.

2. The Zliten MSF plant with three units, each having a distillate production rate of 4525 m³/day, the distillate purity being 25 ppm. This plant being in operation, we shall stress on the occuring maintenance problems.

All difficulties encountered (during erection for Ganzour plant and during maintenance for Zliten plant) are studied in details. Also the influence of each plant on the development of surrounding regions is considered. Recommendations to both sides (Libyan government and foreign plant manufacturers) are made in order to avoid the future repetition of these problems and troubles.     

Fractionation of partially stereoregular poly(propylene oxide)

Partially stereoregular poly(propylene oxide) samples were synthesized via reactions catalysed by a preformed analytically defined trimethylaluminium hydrolysate. These samples were fractionated into two contrastingly different fractions.

1. (i) D-polymers: This fraction constituted the major part (up to 90%). It mainly contained cyclic low molecular weight oligomers (MW < 1000). The linear chains found in D-polymers had hydroxyl end groups. No double bonds could be detected spectroscopically.

2. (ii) K-polymers: This fraction was high molecular weight stereoregular polymer. Stepwise thermal precipitation from dilute isooctane solution of K-polymers yielded a succession of fractions which differed in melting point. It appears that the phase equilibria during the thermal precipitations were not controlled by the molecular weights of species.

Heterogeneous catalysis: looking forward with molecular simulation

Some of the areas in which we anticipate, over the next five years, notable advances in the application of molecular simulation to problems in heterogeneous catalysis are considered, in the context of recent progress to date. The areas specifically addressed are:

• expanding access to methods,

• quantitative structure-property relationships,

• building structural models to focus or pre-screen experiments,

• confidence in predicting local and extended structure

• reaction mechanisms, barriers and kinetics, and

• data for chemical process simulations.

In each of these areas, we indicate why we consider the topic significant, provide reference to topical work and suggest opportunities for future developments.     

Kinetic studies using temperature-scanning: the oxidation of carbon monoxide

We report on an experimental investigation of carbon monoxide oxidation over a 0.05% Pt/γ-Al₂O₃ catalyst using a temperature scanning reactor (TSR) to increase the rate of data acquisition. Temperature scanning (TS) allows us to complete an experimental study of the kinetics of this reaction on one catalyst, at one pressure and feed composition, in less than one working day of fully automated reactor operation. Real-time measurement of CO conversion was done using a quadruple mass spectrometer (MS).

The kinetics of this reaction were quantified by using 12,300 conversion–rate–temperature (X, r, T) triplets calculated from raw data obtained using our TS-PFR, and fitting those with two proposed mechanistic rate equations. Due to the large volume of data and the methods of interpretation used in temperature scanning, we will present our results not only in terms of the traditional curves in the conversion–space time (X, τ) plane but also nitroduce the concept of three-dimensional kinetic surfaces, such as the (X, r, T) surface.

The experimental rate data were correlated using two mechanistic rate models:

1. the Langmuir–Hinshelwood dual site molecular adsorption model (MAM), and

2. the Langmuir–Hinshelwood dual site dissociative adsorption model (DAM).

The models differ only in their view of the state of the adsorbed oxygen. The DAM model, which involves the reaction of oxygen atoms with carbon monoxide molecules, both adsorbed on the same type of site, was found to fit our experimental data over a broader range of reaction conditions and feed compositions. The MAM model, which presumes a reaction of carbon monoxide molecules with adsorbed molecular oxygen, can fit experimental rates well for individual feed ratios but not over the range of feed ratios used in our study. We therefore, propose that the rate-controlling step in this mechanism consists of a reaction between adsorbed carbon monoxide molecules and adsorbed oxygen atoms.     

Hydrotreating processes for catalytic abatement of water pollutants

Opportunities and problems in application of catalytic hydrotreating processes, which are presented a viable approach in the abatement of water pollutants, are discussed. Analysis of the hydrodechlorination (HDC) and hydrodenitrification (HDN) using Pd-based catalysts supported on various materials like granulated activated carbon (GAC), fibrous activated carbon cloths (ACCs) or glass fiber cloths (GFCs) studied recently in our laboratory suggests the following perspectives:

Exhaustive regeneration of Pd/GAC saturated with p-chlorophenol can be achieved in a two-step approach, incorporating gas-phase HDC by hydrogen followed by oxidation by air.

Pd/ACC catalysts are good candidates for the liquid-phase HDC showing activity higher than that of Pd/GAC or Pd/GFC; the high adsorption capacity of Pd/ACC lead suggesting its use in a technology with periodic adsorption and HDC, in similarity to adsorption with regeneration of GAC.

Pd/GFC and Pd–Cu/GFC are promising catalyst for removal of nitrites and nitrates, showing activity and selectivity that compares favorably with those of powdered catalysts.

A new look at dual purpose, water and power, plants - economy and design features

In light of rapidly rising equipment and fuel costs, recent studies have shown some important results in the economy and optimum designs for dual purpose power/desalting complexes. The desalination cycle chosen for- detailed comparisons in this study is the well known multistage flash (MSF) evaporator, which uses brine recirculation and polyphosphate scale prevention. The multi- stage flash evaporator has found wide spread application in large plants throughout the world. Single units of up to 1400 m3/hr (9.5 MGD), acid dosing, have been built and are now in operation. In general due to corrosion problems, polyphosphate plants are now preferred over the acid one.

A number of schemes for the combined production of power and. water were chosen, mainly a combination of MSF Unit with each of the following power cycle:

• 1- Automatic extraction steam turbine

• 2- Simple gas turbine with waste heat boiler

• 3- Back pressure steam turbineThis paper presents a study of the economic aspects, thermodynamic features and optimization analysis of each of these combined power and water production plants.

The optimum value of the performance ratio and its effect on reducing the cost of water in each of the above mentioned schemes would be discussed in this paper.     

Volatility and chemistry of trace elements in a coal combustor

The volatility of 16 trace elements (TEs) (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, Te, Tl, V, Zn) during coal combustion has been studied depending on the combustion conditions (reducing or oxidizing) and type of coal (high- or low-ash coal), together with their affinities for several active gaseous atoms: Cl, F, H, O, and S.

The elements can be divided into three groups according to their tendencies to appear either in the flue gases or in the fly ashes from a coal combustor:

Group 1: Hg and Tl, which are volatile and emitted almost totally in the vapor phase.

Group 2: As, Cd, Cu, Pb and Zn, which are vaporized at intermediate temperature and are emitted mostly in fly ashes.

Group 3: Co, Cr, Mn and V, which are hardly vaporized and so are equally distributed between bottom ashes and fly ashes. In addition, Sb, Sn, Se and Te may be located between Groups 1 and 2, and Ni between 2 and 3.

At 400 and 1200 K, the 16 TEs behave differently in competitive reactions with Cl, F, H, O and S in a coal combustor.     

Application of infrared ATR spectroscopy to in situ reaction monitoring

The infrared horizontal ATR technique was adapted to be applied for in situ reaction monitoring even at high pressure and high temperature. Different types of reactors and flow cells were built which can be used for recording IR ATR spectra at pressures up to 200 bar and temperatures up to 300°C.

The use of the horizontal ATR technique is shown by the following application examples:

• addition reaction of n-butyl isocyanate with butyric alcohol;

• investigation of the equilibrium of isocyanate, HCl and carbamic acid chloride at elevated pressure and temperature;

• monitoring the polycondensation of bifunctional alcohols and carbonic acids;

• recording spectra of polymer melts at 280°C.

Implementation of ISO 14001:2004 (environmental management system standard) for reverse osmosis desalination plants for the first time in Iran

Implementation of ISO 14001:2004 (environmental management system) has been executed for reverse osmosis desalination plants for the first time in Iran at Noor Vijeh Company (N.V. Co), a water and wastewater firm based in Tehran. The scope of work was the activities and product of company's BWRO desalination plant in the city of Qom (3000 m³ per day) and SWRO desalination plant in Assaluyeh, Pars Special Economic and Energy Zone, Iran. The aims of this project were in line with company’s approach to sustainable development and its direction towards conducting environmental friendly activities and production characteristics.

Initially the famous PDCA (Plan, Do, Check, Act) was used to identify the aspects and evaluate their effects. The significant aspects of each plant affecting the environment are then identified and preventive control measures and reducing their probabilities of loss are anticipated. These cover the normal activities within each plant and those aspects arising from emergency conditions such as earthquakes, fire, etc.

Elements of this system are

• Environmental policy and its targets and programmes

• Practical methods for environmental management system processes

• Executive manuals for implementing special activities

• Tables and indexes for environmental aspects for each plant

• Organizational charts, positions, qualifications, and necessary trainings for the involved personnel.

Environmental aspects are evaluated through their interaction with and effects over, releases to water, emissions to air, land contamination, waste management, energy use, and use of natural resources and raw material.     

On the reduction of desalting energy and its cost in Kuwait

All seawater desalting processes, multi-stage flash (MSF), multi-effect boiling (MEB), mechanical vapor compression (MVC) and seawater reverse osmosis (SWRO) consume significant amounts of energy. The recent increase of fuel oil cost raises the cost of energy consumed for desalting water and the final water cost, and creates more interest in using more energy efficient desalting systems.

The most used desalting systems by distillation (MSF and MEB) are usually combined with power plants in what is called co-generation power desalting plants, CPDP. Fuel is supplied to the CPDP to produce both desalted water D and power W, and the fuel cost is shared between D and W. Exergy analysis and equivalent work are among the methods used to determine the fuel energy charged to each product. When desalting systems, such as SWRO and MVC, are not combined with a power plant, the fuel energy can be directly determined from its electrical power consumption.

In this paper, the fuel energy cost charged to desalting seawater in the presently used CPDP in Kuwait is calculated based on exergy analysis. The MSF, known by its high energy consumption, is the only desalting method used in Kuwait. The MSF units consume 258 kJ/kg thermal energy by steam supplied to the brine heater BH, 16 kJ/kg by steam supplied to steam ejectors, and 4 kWh/m3 mechanical energy for pumping. These MSF units are operated either by:

(1) Steam extracted from extraction/condensing steam turbines EC/ST as in as in Doha West, Azzour, and Sabbiya CPDP. This practice is used in most Gulf area.

(2) Steam supplied directly from boilers as occurred in single purpose desalting plants as Al Shuwaikh plant; or in winter time when no steam turbines are in operation in the CPDP to supply steam to the desalting units.

The CPDP have limited water to power production ratio. While they can cope with the increase of power demand, it cannot satisfy the water demand, which is increasing with higher pace than the power demand.

The case of steam CPDP used in Kuwait is presented in this paper as a reference plant to evaluate the amount of fuel energy consumed to desalt water in MJ/m3, its cost in $/m3. The resulted high fuel cost calls for some modifications in the reference CPDP to lower the energy cost, and to increase its water to power ratio. The modifications include the use of an auxiliary back-pressure steam turbine ABPST supplied with the steam presently extracted to the MSF units. The power output of the ABPST operates MVC or SWRO desalting units; while the ABPST discharged steam operates LT-MEB desalting unit. The desalting fuel energy costs when applying these modifications are also calculated by the exergy analysis and compared with that present situation.

It is also suggested to increase desalted water output by using separate SWRO desalting units operated by the existing power plants of typical η_c = 0.388, or by new combined gas/steam turbines power cycle GT/ST-CC of typical η_c = 0.54 under construction. The SWRO with energy recovery is assumed to consume typical 5.2 kWh/m³ electric energy.     

Pilot filtration study to reduce fouling on Marbella seawater RO plant

The seawater RO plant at Marbella had operated intermittently, and at low flowrates, since its construction 10 years ago. This was because the plant had been designed to operate at times of water shortage, to provide water when the conventional supplies were not available.

During the early part of the 21st century, the mode of the plant changed, and it was expected to operate at design capacity for most of the time. This brought two facts to light — that during high abstraction rates the intake water quality deteriorated significantly, and that the filtration system that had been installed was not capable of adequately filtering the feed water to make it suitable for feeding to a reverse osmosis plant.

The plant was originally built using DuPont B10 permeators. Due to the unavailabilty of these permeators, the plant is currently being converted, stream by stream, to spiral wound membranes supplied by Hydranautics.

At design flowrates, the DuPont system fouled rapidly, and required cleaning every two weeks. The spiral trains fouled more slowly, but still required cleaning at a higher frequency than would be considered normal for this type of plant.

A pilot filtration plant was installed on site to attempt to find the following;

• An optimum coagulant for the water.

• An approximate dose rate for that coagulant.

• The effect of different media on the quality of filtered water.

• The length of run between backwashes using different media.

• The quality of water that can be achieved using this coagulant and media.

By installing pressure tapping points along the length of the filter, the area of differential pressure could be measured. This was used to ensure depth filtration was taking place, and the foulants were being removed through the length of the bed rather than surface filtration.

The trials lasted a total of three months and achieved all of the targets set. The SDI typically achieved by the main plant was approximately 5. The pilot filter showed that the SDI could be reduced to below 2 by modifying the filters and applying a coagulant. Filter runs achieved by the pilot filters were in excess of 48 h.

Following the trials, the plant commenced replacing the media in the filtration system, and is expected to install a coagulant dosing system once this was complete.

This paper describes the pilot plant built, the selection of the media, and the coagulants used, and presents the operating data produced from the trials.     

Teaching and learning strategies and evaluation changes for the adaptation of the Chemical Engineering degree to EHES

An integrated learning methodology has been developed and implemented in order to adapt the Chemical Engineering degree in the University of Valladolid (Spain) to the European Higher Education Space (EHES) philosophy. It was necessary to modify the objectives and theoretical contents of the different subjects and also the learning methodology, considering the general chemical engineering skills and also the transferable skills reached by the students, according to the recommendations of the European Federation of Chemical Engineering (EFCE) for chemical engineering education in Bologna two-cycle degree system.

This methodology has been applied to the seventh semester of a 5 years Chemical Engineering degree. The main objectives of the proposed strategy were:

• To provide to the student with a holistic, integrated and applied vision of the different subjects involved in chemical engineering, coordinating all of them and planning common activities as a case study based on an industrial process.

• To help students to develop transferable skills by means of designing suitable teaching and learning strategies.

• To prepare the students for the long-life learning.

General and particular objectives were defined adapting the course to the EHES philosophy. In this sense, the programmes in terms of the learning outcomes and competences to be acquired were designed, the total student workload to get the objectives of the programme was estimated and the entire course was programmed and planned in a detailed schedule. A course guide was elaborated including all this information, resulting in a useful instrument for teachers and students.

This methodology was complemented with the evaluation of the global learning process. The evaluation made was based on the next two aspects:

• Student learning evaluation. Tutorial sessions, written reports, oral presentations, discussion sessions and partial and final written exams were considered.

• Learning methodology evaluation. External evaluation requires carrying out inquiries, both to students and teachers involved.

Fluidized bed coating and granulation: influence of process-related variables and physicochemical properties on the growth kinetics

This study, which deals with the coating and granulation of solid particles by aqueous solutions of polymers or inorganic salts, aims to understand the effect of:

process-related variables such as the excess gas velocity, atomizer location, liquid flow rate and concentration, and atomizing air flow rate,

physicochemical-related variables such as the viscosity of solutions, wettability of the granulating liquid on solid particle surfaces, initial particle mean size, and porosity of the particles on the agglomeration kinetics of solid particles in a fluidized bed.

The results showed that for a given particle size, the fluidizing air velocity was the most important factor affecting the growth kinetics and the stability of the operation. An increase of the relative humidity, depending on the liquid flow rate as well as the air flow rate, favor agglomeration mechanism especially for values greater than 0.4. An increase in the particle initial size leads to an enhancement of the layering mechanism, especially for values greater than 300 μm.

The effect of the interfacial tension is investigated by adding different concentrations of a non-ionic surfactant to the binding solution. The effect of the contact angle is then studied using non-hydrophobic, partly hydrophobic, or totally hydrophobic particles. The growth of agglomerates appears to be favoured when the interfacial tension increases and the contact angle decreases. The viscosity of the solution has less effect than the interfacial parameters. The results show that the dominant forces in the granulation process are the capillary forces.     

二氧化碳与不饱和烃制备丙烯酸及其衍生物研究进展

CO₂高值转化是“双碳”目标大背景下碳利用的有效方式。过渡金属络合物催化的CO₂与不饱和烃羧化反应是合成丙烯酸及其衍生物的新路线,也是CO₂高值利用的新途径。本文总结了多种金属络合物（Ni、Pd、Cu等）在催化CO₂与烯烃偶联羧化、CO₂与炔烃或联烯还原羧化制丙烯酸及其衍生物中的应用,着重概述了不同催化体系中的金属-配体优化和反应条件调控,系统对比了不同催化剂的催化特点和作用机制,并论述了其催化反应循环中的控速步骤以及催化剂再生等关键问题。最后,对过渡金属络合物催化CO₂与乙烯偶联羧化制备丙烯酸及CO₂与炔烃或联烯还原羧化合成高区域选择性不饱和羧酸衍生物的后续研究方向和应用前景进行了展望。     

Thermal- and photoinduced ring-opening metathesis polymerization (ROMP)/(PROMP): an efficient tool in polymer chemistry

Properties and applications of newly developed homogeneous ring-opening metathesis polymerization catalysts as well as photoinduced ring-opening metathesis polymerization catalysts are discussed. It is shown that simple alkyl complexes, e.g. [W(=NPh)(CH₂SiMe₃)₃Cl] as well as [Ru(arene)₂]²⁺ or [Ru(NC–R)₆]²⁺ complexes act as one-component Photo-ROMP initiators. Catalysts with good thermal latency are described for both classes. High quantum yields are observed for the photochemically induced solvation of Ru(II) complexes. Polymer structure and kinetic aspects of the reaction are consistent with [Ru(solvent)₆]²⁺ acting as the catalytically active species. The mechanism of aqueous ROMP with Ru(II) salts is discussed, which differs considerably from the classical ROMP reaction with Schrock-type catalysts in the sense that it is a chain reaction and not a living polymerization. Homo- and copolymers using exo-oxa-norbornene-carboximide ester derivatives were prepared with the ROMP technology and used, inter alia, to formulate very sensitive positive tone high-resolution microresists.