Rich Stream Research Articles

Hydrogen production from crude pyrolysis oil by a sequential catalytic process

A sequential process aiming at hydrogen production was studied over two Ni-based catalysts, using crude beech-wood oil as the feed. The process alternates cracking/reforming steps, during which a H2+CO rich stream is produced and carbon is stored on the catalyst, with regeneration steps where the carbon is combusted under oxygen. The two catalysts exhibited good performances for H2 production from bio-oil, the gaseous products stream consisting in 45–50% H2. The regeneration step was found fast and efficient, the coke being readily combusted and the catalyst activity fully recovered. A positive heat balance between the endothermic cracking/reforming reactions and the exothermic coke combustion suggests that an autothermal process could be designed. Comparison of the thermal decomposition of bio-oil (empty reactor) with the catalytic cracking revealed that they are first decomposed into primary light gases (CO, CO2, CH4, C2+) and soots. These compounds are further reformed onto the catalyst by the steam contained in bio-oil, and equilibrated via the WGS reaction. The key roles of the catalyst are therefore (i) to improve the overall bio-oil gasification into syngas, (ii) to promote steam reactions and increase hydrogen production by steam reforming and WGS and (iii) to control and determine the nature of the coke formed during the cracking/reforming step. A Ni/Al2O3 catalyst with large Ni particles was found to promote the formation of carbon filaments, whereas on a Ni–K/La2O3–Al2O3 catalyst, with a lower Ni loading and highly dispersed Ni, the carbon was essentially deposited as an amorphous carbon layer.

High Tech Trash: Digital Devices, Hidden Toxins, and Human Health

By Elizabeth Grossman Washington, DC:Island Press, 2006. 334 pp. ISBN: 1-55963-554-1, $25.95 In High Tech Trash, Elizabeth Grossman traces the effects of the high-tech computer industry on the environment, from the raw materials to the chemicals and solvents used to produce silicone chips as well as other persistent organic compounds used to produce high-tech equipment. Grossman then describes the subsequent recycling of electronics for reuse as well as the recovery and recycling of raw materials such as copper, zinc, gold, and plastics. This journey through electronics, which formerly had been recognized as a “clean” industry, begins in the mines that supply many of the raw materials—including copper, aluminum, lead, gold, zinc, nickel, tin, silver, and iron—used in modern electronics. Grossman then discusses the different chemicals and solvents used in the production of silicone chips. She gives a close-up view of the electronics industry, recognizing the improvements in chemical safety from the early days when many of the tasks involving solvents such as trichloroethylene (TCE) and trichloroethane (TCA) were performed manually. These improvements have helped ensure that workers’ exposures to chemicals have been substantially reduced in the automated factories of today. Grossman further points out that the groundwater at current Superfund sites is now contaminated with TCE and TCA as a result of leaks and spills that occurred in the early days of the electronics industry. The fact that several residential areas once drew drinking water from these sites and that vapors may pass upward from soil to air has, says Grossman, affected thousands of people. In her review of the available literature on polybrominated diphenyl ethers (PBDEs), Grossman discusses the likely link between human exposure to PBDEs and the high levels of PBDEs in residential dust. Unfortunately, Grossman frequently uses the generic term “PBDEs” rather than specifying which congeners are present in the technical-grade preparation of the PBDEs she discusses. Primarily, technical-grade octabromodiphenyl ether (octaBDE) and decabromodiphenyl ether (decaBDE) are used in the plastic housings of electronics, whereas technical-grade pentabromodiphenyl ether (pentaBDE) is used primarily in polyurethane to manufacture foam and padding materials. The congeners present in the pentaBDE mixture have been shown to accumulate in biological tissues, but the PBDEs in octaBDE and decaBDE have much shorter half-lives in people and are unlikely to biomagnify, although they are detectable in many human tissues. The chapters on recycling and on the flow of electronic waste from consumers to landfills and the export of waste to developing countries are well written and detailed. For example, Grossman states that the United States discards enough electronic waste annually to cover a football field a mile high and that of this waste, only 10% is recycled for materials recovery. Most of the waste goes to landfills or to waste incinerators. Grossman describes the handling of electronic waste that is exported from developed countries into developing countries and the tremendous environmental impact this waste has had in certain countries. For example, in Taizhou in southern China, circuit boards containing lead, flame retardants, and plasticizers are melted for the recovery of metals in uncovered pans only steps away from the workers’ dormitories. In addition, the author offers an interesting description of the different recycling processes used by industrial companies such as Boliden Mineral AB in Sweden and Noranda in the United States. These companies have discovered a “rich ore stream” in the circuit boards they “mine” for metals. Clearly, the increasing tide of electronic waste will be brought under control only if all parties involved (manufacturers, legislators, consumers, and recyclers) implement improvements such as reducing the amount of hazardous materials used in the manufacture of electronic products, producing electronics that are easier to disassemble for recycling, enacting legislation governing the electronics and recycling industries, and ensuring that consumers are informed about the issues associated with the production of electronics and with electronic waste so they can make educated decisions about the issues. Unfortunately, we have just now begun to address these issues, and changes will not be quick or easy.

MnOx/Pt/Al2O3 catalysts for CO oxidation in H2-rich streams

The catalytic activity of Pt on alumina catalysts, with and without MnOx incorporated to the catalyst formulation, for CO oxidation in H2-free as well as in H2-rich stream (PROX) has been studied in the temperature range of 25–250°C. The effect of catalyst preparation (by successive impregnation or by co-impregnation of Mn and Pt) and Mn content in the catalyst performance has been studied. A low Mn content (2wt.%) has been found not to improve the catalyst activity compared to the base catalyst. However, catalysts prepared by successive impregnation with 8 and 15wt.% Mn have shown a lower operation temperature for maximum CO conversion than the base catalyst with an enhanced catalyst activity at low temperatures with respect to Pt/Al2O3. A maximum CO conversion of 89.8%, with selectivity of 44.9% and CO yield of 40.3% could be reached over a catalyst with 15wt.% Mn operating at 139°C and λ=2. The effect of the presence of 5vol.% CO2 and 5vol.% H2O in the feedstream on catalysts performance has also been studied and discussed. The presence of CO2 in the feedstream enhances the catalytic performance of all the studied catalysts at high temperature, whereas the presence of steam inhibits catalysts with higher MnOx content.

Activity and stability enhancement of copper–alumina catalysts using cerium and zinc promoters for the selective production of hydrogen via steam reforming of methanol

The catalytic activity and hydrogen selectivity of cerium and zinc promoted copper–alumina catalysts have been investigated for the selective production of hydrogen via steam reforming of methanol (SRM). The SRM was carried out in a fixed bed tubular reactor at atmospheric pressure over a temperature range 200–300 °C. The major reaction products were hydrogen and carbon dioxide with traces of carbon monoxide. Catalysts of varying compositions were prepared by the wet impregnation method and characterized by atomic absorption spectroscopy (AAS), BET surface area, pore volume, pore size, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and thermogravimetry analysis (TGA). Results revealed that the methanol conversion, hydrogen selectivity and carbon monoxide formation varied with the type of promoter and content of copper in the catalyst. Cerium promoted Cu–Zn–Ce–Al-oxide catalysts improved the activity and hydrogen selectivity greatly and also kept the CO formation very low. Using cerium the SRM could be carried out at lower temperature with high methanol conversion, results in suppression of methanol decomposition and reverse water gas shift reactions eventually end-up with the low carbon monoxide and hydrogen rich product stream. Cerium also stabilizes the copper–alumina catalysts effectively that was confirmed by deactivation studies in which cerium promoted Cu–Zn–Ce–Al-oxide catalysts gave the consistent performance for a long run-time compared to catalysts containing only zinc promoter. The optimum operating conditions for SRM have been investigated by detailed study of effects of reaction temperature, contact time and steam to methanol molar ratio on methanol conversion, hydrogen selectivity and CO formation. Reaction pathway has been proposed for the SRM based on results obtained.

Hydrogen Clean-up by Preferential CO Oxidation over Pt–Co–Ce/MgO

1.4 wt% Pt–1.25 wt% Co–1.25 wt% Ce catalyst on MgO support was prepared using incipient to wetness impregnation technique and tested in a micro-reactor flow system for the low temperature preferential oxidation of CO in hydrogen rich streams. 100% CO conversion was achieved at 130 °C with a feed composition of 1.0% CO, 1.0% O2, 60% H2 and He as balance at a space velocity of 24,000 cm3/g-h. The addition of 25% CO2 did not affect the performance of the catalyst significantly, while 10% H2O in the feed decreased the activity. 100% CO conversion was obtained at 150 °C in the presence of 25% CO2 and 10% H2O in the feed.

Increasing the Effectiveness of Communications to Consumers: Recommendations Based on Elaboration Likelihood and Attitude Certainty Perspectives

This article makes suggestions about how to effectively communicate the risks associated with products and services to consumers. The authors realize this goal by drawing on several rich streams of literature on the psychology of persuasion. Specifically, they provide guidelines for developing effective communications based on the elaboration likelihood model of persuasion and integrating emerging research on attitude certainty. On the basis of these research areas, the authors further discuss how to diagnose why a particular communication may not have proved effective. Finally, they provide examples to help illustrate the actual steps policy makers and others might take in developing communications to warn or inform consumers.

Energy deposition effect on the NOx remediation in oxidative media using atmospheric non thermal plasmas

Dielectric barrier discharges (DBDs) have been investigated under a wide range of experimental conditions (pulsed and sinusoidal excitation, input energy, frequency, and residence time) to remediate NOx from atmospheric O 2 rich gas streams. In a given reactor under identical gas composition and equivalent energy density deposition, results show that the main parameter which controls the efficiency of the plasma process is the energy deposition mode. For example, in a pulsed DBD processing at energy density deposition of 30 J/L, 25% of NOx and 40% of C 3 H 6 were converted at 35 mJ/pulse whereas, at 195 mJ/pulse these values were 0% and 15%, respectively. Furthermore, significantly different end products were observed when changing the nature of electrical excitation.

Aroma recovery by combining distillation with absorption

A new method for aroma recovery during evaporation is presented, in which, the vapour generated in an evaporator passes through an absorber where a hygroscopic solution partially absorbs water vapour. The remaining aroma rich stream is subsequently condensed. Experiments were carried out using 60% LiBr solution as hygroscopic solution and methanol, ethanol, ethyl acetate, methyl butyrate and ethyl butyrate as aroma compounds. When 20% of the feed was evaporated the aroma compounds were completely stripped from the feed, while when 10% of the feed was evaporated methanol and ethanol partially stripped from the feed. A significant amount of methanol and ethanol was absorbed by the LiBr solution (21–46%), while 3–17% of ethyl acetate, methyl butyrate and ethyl butyrate, compounds of higher relative volatility, were absorbed. The relative concentration of the aroma compounds, Ci/(Cfeed)i, in the condensate was 1.8–2.8 times higher than in the condensate obtained from comparative simple distillation experiments.

Improved ethanol–water separation using fatty acids

As a means to reduce the processing costs for separating ethanol from fermentation broth, several fatty acids have been tested as liquid solvents for extracting ethanol from water. Valeric acid, the lowest molecular weight fatty acid used in this study, extracted the most ethanol but was not an ideal solvent since it also extracted water and was quite soluble in water. Oleic acid, the highest molecular weight fatty acid used in this study, was not soluble in water but was not a good solvent because it extracted low amounts of ethanol. Nonanoic acid was found to be the best extracting solvent, providing a reasonable ethanol distribution coefficient (0.354) and a 69.5% vapour rich ethanol stream using flash separation. Nonanoic acid extraction combined with the flash process is shown to require 38% less thermal energy to separate an equivalent amount of ethanol from fermentation broth compared to the traditional distillation process.

Determination of Mass Separating Agent Flows Using the Mass Exchange Grand Composite Curve

In this paper we set out the principles for using the grand composite curve (GCC) of mass exchange network synthesis (MENS) for selection of external mass separating agents (MSAs). These principles enable us to systematically choose between alternative external MSAs as well as the minimum flowrate for each MSA selected. This paper emphasizes that the cheapest MSA is not necessarily the one with the lowest cost per unit mass of MSA, but rather the one with the lowest overall cost of removal of the mass load, which depends on both the MSA cost and its permissible concentration change. It also demonstrates the importance of consideration of the composition levels of the MSAs in relation to the target compositions of the rich streams and to the capital cost implications of the resulting mass transfer driving forces. In this respect the use of the GCC is superior to procedures developed so far. We illustrate the principles presented by application to two example problems.

Defocus video matting

Video matting is the process of pulling a high-quality alpha matte and foreground from a video sequence. Current techniques require either a known background (e.g., a blue screen) or extensive user interaction (e.g., to specify known foreground and background elements). The matting problem is generally under-constrained, since not enough information has been collected at capture time. We propose a novel, fully autonomous method for pulling a matte using multiple synchronized video streams that share a point of view but differ in their plane of focus. The solution is obtained by directly minimizing the error in filter-based image formation equations, which are over-constrained by our rich data stream. Our system solves the fully dynamic video matting problem without user assistance: both the foreground and background may be high frequency and have dynamic content, the foreground may resemble the background, and the scene is lit by natural (as opposed to polarized or collimated) illumination.

Conversion of a Naphtha Reformer Unit to Butane Isomerization

A study was carried out for the conversion of a naphtha reformer unit to a butane isomerization plant, where a normal butane rich stream is isomerizated to isobutane. This compound has a bigger added value when it is used in an alkylation process to produce a high octane alkylated fuel, which is used as an adjustment component in high octane gasoline blending. Basically the new isomerization unit will work with a conventional process scheme. Nevertheless, some adaptations in the loading preparation section are included in this study, in order to fit up the process load because its high light components content, specifically propane. An equipment pre-sizing and current equipment reusing analysis at the process condition specifications are also included. Technically, it is concluded that the conversion is feasible because most of the existing equipment can be used. Finally, the analysis was complemented with an economic study in order to determinate the profitability of the existing plant conversion against the construction of a new one. Conversion resulted in being the most profitable option, requiring an investment equivalent to 70% from that corresponding for a new plant construction, with a 48.14 internal rate of return, and 1 year and 5 months investment recovery period.

A comparative study of [formula omitted] and [formula omitted] catalysts for the catalytic oxidation of CO in hydrogen rich stream

A comparative study of the catalytic activity and stability of two types of metal oxides supported Au catalysts for selective CO oxidation in the presence of hydrogen has been studied with the simulated reformed gas in the temperature range of 50–190 °C. Effects of CO 2 and H 2O in the feed gas on the catalytic activity of both catalysts as well as catalytic stability were compared. It was found that Au / MnO x gave 93% conversion and 58% selectivity at 130 °C while Au / FeO x gave 98% conversion and 53% selectivity at 50 °C. Interestingly, both catalysts could resist up to 10%H 2O in the reactant feed while their activities were suppressed in the presence of 20%CO 2. The deactivation was not observed during a 48 h stability test for both catalysts.

Preparation of Au/TiO2 for catalytic preferential oxidation of CO under a hydrogen rich atmosphere at around room temperature

Au/TiO2 prepared in a pH adjusted gold solution by a deposition-precipitation method can possess high activity and stability for selective CO oxidation in a H2 rich stream at ambient temperature.

Research on information technology in the hospitality industry

This paper reviews recent research on information technology in the hospitality industry. The analysis revealed three broad research areas: the Internet's effects on distribution; on pricing; and on consumer interactions. Similar to aftermath of the dot com boom, the hospitality industry is realising that the information technology has unintended effects and prognosticators are often wrong. While the reviewed articles provide sound advice for hospitality operators and a rich stream of future research for academics, poor rigor and a lack of relevance throughout the reviewed journals underscore a worrying trend in hospitality research.

Oil-Water Separation in a Novel Liquid-Liquid Cylindrical Cyclone (LLCC©) Compact Separator—Experiments and Modeling

The hydrodynamics of multiphase flow in a Liquid-Liquid Cylindrical Cyclone (LLCC) compact separator have been studied experimentally and theoretically for evaluation of its performance as a free water knockout device. In the LLCC, no complete oil-water separation occurs. Rather, it performs as a free-water knockout, delivering a clean water stream in the underflow and an oil rich stream in the overflow. A total of 260 runs have been conducted, measuring the LLCC separation efficiency for water-dominated flow conditions. For all runs, an optimal split-ratio (underflow to inlet flow rate ratio) exists, where the flow rate in the water stream is maximum, with 100% watercut. The value of the optimal split-ratio depends upon the existing inlet flow pattern, and varies between 60% and 20%. For split-ratios higher than the optimal one, the watercut in the underflow stream decreases as the split-ratio increases. A novel mechanistic model has been developed for the prediction of the complex flow behavior and the separation efficiency in the LLCC. Comparisons between the experimental data and the LLCC model predictions show excellent agreement. The model is capable of predicting both the trend of the experimental data as well as the absolute measured values. The developed model can be utilized for the design and performance analysis of the LLCC.

Novel concepts for CO 2 capture

This paper describes the possibilities for power generation with CO 2 capture using envisaged key technologies: gas turbines, membranes and solid oxide fuel cells (SOFCs). First, the underlying programs in the Netherlands and at ECN are introduced. Then the key technologies are introduced, and concepts using these technologies are discussed. A literature overview of systems for power generation with fuel cells in combination with CO 2 capture is presented. Then a novel concept is introduced. This concept uses a water gas shift membrane reactor to convert the CO and H 2 in the SOFC anode off-gas to gain a CO 2 rich stream, which can be used for sequestration without elaborate treatment. Several implementation schemes of the technique are discussed such as atmospheric systems and hybrid SOFC–GT systems.

Reach‐scale isotope tracer experiment to quantify denitrification and related processes in a nitrate‐rich stream, midcontinent United States

We conducted an in‐stream tracer experiment with Br and 15N‐enriched NO3− to determine the rates of denitrification and related processes in a gaining NO3− ‐rich stream in an agricultural watershed in the upper Mississippi basin in September 2001. We determined reach‐averaged rates of N fluxes and reactions from isotopic analyses of NO3−, NO2−, N2, and suspended particulate N in conjunction with other data in a 1.2‐km reach by using a forward time‐stepping numerical simulation that included groundwater discharge, denitrification, nitrification, assimilation, and air‐water gas exchange with changing temperature. Denitrification was indicated by a systematic downstream increase in the δ15N values of dissolved N2. The reach‐averaged rate of denitrification of surface‐water NO3− indicated by the isotope tracer was approximately 120 ± 20 µmol m−2 h−1 (corresponding to zero‐ and first‐order rate constants of 0.63 µmol L−1 h−1 and 0.009 h−1, respectively). The overall rate of NO3− loss by processes other than denitrification (between 0 and about 200 µmol m−2 h−1) probably was less than the denitrification rate but had a large relative uncertainty because the NO3− load was large and was increasing through the reach. The rates of denitrification and other losses would have been sufficient to reduce the stream NO3− load substantially in the absence of NO3− sources, but the losses were more than offset by nitrification and groundwater NO3− inputs at a combined rate of about 500‐700 µmol m−2 h−1. Despite the importance of denitrification, the overall mass fluxes of N2 were dominated by discharge of denitrified groundwater and air‐water gas exchange in response to changing temperature, whereas the flux of N2 attributed to denitrification was relatively small. The in‐stream isotope tracer experiment provided a sensitive direct reach‐scale measurement of denitrification and related processes in a NO3− ‐rich stream where other mass‐balance methods were not suitable because of insufficient sensitivity or offsetting sources and sinks. Despite the increasing NO3− load in the experimental reach, the isotope tracer data indicate that denitrification was a substantial permanent sink for N leaving this agricultural watershed during low‐flow conditions.

Hydrogen production by ethanol steam reforming over a commercial Pd/γ-Al2O3 catalyst

In the present work the reaction of biomass-derived ethanol steam reforming for hydrogen rich gas streams production, over a commercial alumina supported palladium catalyst was investigated. In particular, the dependence of the catalytic activity and selectivity on reaction temperature, H2O/EtOH molar ratio and contact time was studied. In order to evaluate the catalytic stability long-term experiments were also performed. It was found that hydrogen selectivity was proportional to the H2O/EtOH molar ratio and ethanol was completely converted even at relatively low temperature values. Hydrogen selectivities up to 95% were obtained at temperature values close to 650°C. It was also observed that for the examined H2O/EtOH molar ratios, carbon monoxide concentration exhibits for thermodynamic reasons a minimum at a temperature value close to 450°C. Furthermore, carbon formation was found to be negligible even for H2O/EtOH molar ratio equal to the stoichiometric one. On the contrary, as water to ethanol ratio in the feed stream was decreased below the stoichiometric, carbon rate formation was increased resulting in catalyst deactivation.

Low temperature CO oxidation in hydrogen rich streams on Pt-SnO 2/Al 2O 3 catalyst using Taguchi method

Taguchi method of experimental design was used to optimize the catalyst preparation conditions of the sol–gel method to design a Pt-SnO 2/Al 2O 3 catalyst for the low temperature oxidation of carbon monoxide in hydrogen rich stream. HNO 3, H 2O, aluminum nitrate concentrations and the stirring rate in sol–gel process were optimized to obtain the maximum CO conversion using Taguchi method. It was found and experimentally verified that lower levels of HNO 3 and H 2O concentrations and higher levels of aluminum nitrate concentration and stirring rate maximized CO conversion without inversely affecting selectivity. The effects of reaction conditions such as temperature, time-on-stream, O 2 concentration, CO concentration and space velocity on CO conversion and selectivity were also investigated in a microreactor flow system using the optimum catalyst obtained. A 100% CO conversion was obtained with reasonable selectivity at a temperature of 100 °C, CO concentration of 0.5–1.1%, O 2/CO ratio of about 2 and space velocity of 24,000 cm 3/(g h).