[雙語翻譯]化學(xué)專業(yè)外文翻譯--在振動中羰基化反應(yīng)的催化起始階段（英文）

1、Hindawi Publishing Corporation International Journal of Chemical Engineering Volume 2011, Article ID 518592, 11 pages doi:10.1155/2011/518592Research ArticleCatalyst Initiation in the Oscillatory Carbonylation ReactionKa

2、tarina Novakovic and Julie ParkerSchool of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle upon Tyne NE1 7RU, UKCorrespondence should be addressed to Katarina Novakovic, katarina.novakovic@nc

3、l.ac.ukReceived 16 March 2011; Revised 21 April 2011; Accepted 26 April 2011Academic Editor: D. Yu. MurzinCopyright © 2011 K. Novakovic and J. Parker. This is an open access article distributed under the Creative Co

4、mmons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Palladium(II) iodide is used as a catalyst in the phenylacetylene oxid

5、ative carbonylation reaction that has demonstrated oscillatory behaviour in both pH and heat of reaction. In an attempt to extract the reaction network responsible for the oscillatory nature of this reaction, the system

6、was divided into smaller parts and they were studied. This paper focuses on understanding the reaction network responsible for the initial reactions of palladium(II) iodide within this oscillatory reaction. The species r

7、esearched include methanol, palladium(II) iodide, potassium iodide, and carbon monoxide. Several chemical reactions were considered and applied in a modelling study. The study revealed the significant role played by trac

8、es of water contained in the standard HPLC grade methanol used.1. IntroductionThe palladium-catalysed phenylacetylene oxidative carbony- lation (PCPOC) reaction stands out in a number of respects. It provides a novel pH

9、oscillator operating in a stirred batch reactor [1–8]. Furthermore, when operating the PCPOC sys- tem in an oscillatory regime high levels of product selectivity are reported compared to operating in a nonoscillatory mod

10、e [6]. The ability to achieve selective product formation in this way is a new and notable result in terms of reaction engineer- ing that, once understood, may be imposed on and exploited in industrially significant reac

11、tions. Moreover, the PCPOC reaction represents the first example of complex molecules synthesised from relatively simple reagents proceeding in a catalytic system in an oscillatory mode. Scientifically this is significan

12、t as all other oscillating processes, including those driven by heterogeneous catalysis, involve the oxidation, hydrogenation, or destruction of complex molecules [3]. In addition to oscillations in pH, the PCPOC reactio

13、n has the capacity to produce significant oscillatory pulses of heat (i.e., 600 J/oscillation) over long periods of time (i.e., days) that may be regulated by the reaction conditions [5, 6, 8]. For that reason, the impor

14、tance of the PCPOC reaction for pH and temperature-responsive “smart materials” and their future applications may be foreseen, for example, in drug delivery [9].The aforementioned results imply the need for a fun- dament

15、al understanding of the PCPOC reaction in order to make use of the observed phenomena and apply the knowledge gained to other systems. The key to achieving this is in obtaining a reaction network (i.e., rate determining

16、reactions in a chemical mechanism) responsible for the oscil- latory nature of the PCPOC reaction. The PCPOC reaction system on initiation consists of seven species: CH3OH, PdI2, KI, NaOAc, CO, Air, and C8H6. Conducting

17、mechanistic modelling studies is difficult due to the large number of species. In this work, a strategy that reduces complexity is applied. The overall system is simplified to a series of subsystems consisting of as litt

18、le as two species. The role of each species in the subsystem and their interaction with other species is investigated experimentally and data obtained are employed in modelling studies. The experimental studies are perfo

19、rmed in standard laboratory glassware with a magnetic stirrer, using HEL MicroNOTE for on-line data logging. BatchCAD software is used for kinetic fitting, modelling and simulation studies. An all-aqueous pH-meter setup

20、consisting of aqueous pH electrode filling solution and aqueous calibration buffers is used in all experiments. The pH values measured with this procedure are often called apparent pH values (pHapp) [10]. The pH measurem

21、ents are employed in the modelling study as hydrogen ion concentration. When water is used as the solvent, hydrogenInternational Journal of Chemical Engineering 31500 1000 500 0Time (min)22. 533. 544. 555. 566. 5pHFigure

22、 2: [KI] = 4.8· 10?1 mol/dm3; [PdI2]if all dissolved = 2.66· 10?3 mol/dm3; COflow = 6 mL/min; 25 mL of water.CO purging PdI2 addition200 150 100 50 0Time (min)56789pHappFigure 3: [KI] = 4.8· 10?1 mol/dm3;

23、[PdI2]if all dissolved = 2.66· 10?3 mol/dm3; COflow = 6 mL/min; 25 mL of dry methanol.25 mL of deionised water, and then 24 mg of PdI2 was added. Approximately 1 h after the addition of palladium(II) iodide, purging

24、 with carbon monoxide (6 mL/min) began. The colour of the solution was initially brown, then over the course of the experiment it became colourless and a black precipitate was observed. The pH results are presented in Fi

25、gure 2.2.4. Dry Methanol as Solvent. This experiment used dry methanol as solvent instead of standard grade methanol. Water was removed from the methanol using molecular sieves (pore size 3 ? A and absorption ≥15%). A st

26、ock solution of KI in methanol was made (8 g of KI and 100 mL of CH3OH), molecular sieves were added (4.672 g), and the mixture was stirred for approximately 20 h. The experiment was performed as follows: 1 g of fresh mo

27、lecular sieves was placed into an empty vial followed by 25 mL of the previously prepared stock solution and 24 mg of PdI2. Carbon monox- ide addition (6 mL/min) commenced approximately 1 h after PdI2 was added. The colo

28、ur of the solution was dark red- brown, and no precipitate was observed. The pHapp results are presented in Figure 3.2.5. Standard Grade “Wet” Methanol as Solvent. In this experiment, potassium iodide (8 g) was dissolved

29、 in 100 mL of methanol. PdI2 (96 mg) was added to this solution and150 100 50 0Time (min)1234567pHappFigure 4: [KI] = 4.8· 10?1 mol/dm3; [PdI2] = 2.22· 10?3 mol/dm3; COflow = 6 mL/min; 25 mL of “wet” methanol.C

30、O purgingPdI2 addition100 80 60 40 20 0Time (min)345678pHappFigure 5: [KI]max = 6.4· 10?1 mol/dm3; [PdI2]if all dissolved = 2.66· 10?3 mol/dm3; COflow = 6 mL/min; 25 mL of dry acetone.stirred for 24 hours. The

31、mixture was then filtered over a 0.2 μm millipore membrane filter. After filtration, 80 mg of PdI2 remained in the solution and 25 mL of this filtered solution was placed in a vial. The mixture was stirred at room temper

32、ature (20?C) for 20 minutes before CO addition started (6 mL/min). The pHapp recorded in this run is presented in Figure 4. Throughout the experiment no black precipitate was visible.2.6. Dry Acetone as Solvent. This exp

33、eriment used acetone which had been previously dried using molecular sieves. A stock solution of 75 mL of acetone, 8 g of potassium iodide, and 4 g of molecular sieves was prepared. It was noticed that the potassium iodi

34、de did not fully dissolve. As before 25 mL of this mixture was placed into a vial along with 24 mg of palladium(II) iodide. The mixture was stirred for approximately 15 min before adding carbon monoxide (6 mL/min). The p

35、Happ results are presented in Figure 5. From these five experiments (Figures 1 to 5), the following observations were made.(i) The drop in pH upon carbon monoxide addition occurs only in the system with a component that