<p><b>六偏磷酸鈉</b>（英語：<span lang="en">Sodium hexametaphosphate</span>，縮寫：SHMP、E編碼：E452(i)），是指六聚體 (NaPO<sub>3</sub>)<sub>6</sub>。商品六偏磷酸鈉是多種聚磷酸鹽的混合物，即多偏磷酸鈉，而六聚物是其中的一種。
</p>


<h2><span id=".E5.88.B6.E5.A4.87"></span><span id="制备">製備</span></h2>
<p>1、磷酸二氫鈉法 由二水磷酸二氫鈉加熱至110～230°C分別脫去兩個結晶水和結構水，再進一步加熱至620°C脫水，生成偏磷酸鈉熔融物，並聚合成六偏磷酸鈉。然後卸出，從650°C冷卻至60～80°C時製片，經粉碎製得六偏磷酸鈉成品。</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ NaH_{2}PO_{4}\cdot 2H_{2}O\rightarrow NaH_{2}PO_{4}+2H_{2}O}}}">
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    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ NaH_{2}PO_{4}\cdot 2H_{2}O\rightarrow NaH_{2}PO_{4}+2H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ 2NaH_{2}PO_{4}\rightarrow Na_{2}H_{2}P_{2}O_{7}+H_{2}O}}}">
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    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ 2NaH_{2}PO_{4}\rightarrow Na_{2}H_{2}P_{2}O_{7}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ Na_{2}H_{2}P_{2}O_{7}\rightarrow 2NaPO_{3}+H_{2}O}}}">
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    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ Na_{2}H_{2}P_{2}O_{7}\rightarrow 2NaPO_{3}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}}">
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              <mo stretchy="false">)</mo>
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                <mn>6</mn>
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      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}}</annotation>
  </semantics></math></span></span></dd></dl><p>2、由五氧化二磷與純鹼按一定比例混合反應，並加熱使其脫聚，生成的六偏磷酸鈉熔體經驟冷製片、冷卻，得到工業六偏磷酸鈉成品。</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ P_{2}O_{5}+Na_{2}CO_{3}\rightarrow 2NaPO_{3}+CO_{2}\uparrow }}}">
  <semantics>
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                <mn>2</mn>
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                <mn>2</mn>
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              <mi mathvariant="normal">O</mi>
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                <mn>3</mn>
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            <mo stretchy="false">↑<!-- ↑ --></mo>
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    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ P_{2}O_{5}+Na_{2}CO_{3}\rightarrow 2NaPO_{3}+CO_{2}\uparrow }}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}}">
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    <mrow class="MJX-TeXAtom-ORD">
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            <mtext> </mtext>
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            <mo stretchy="false">→<!-- → --></mo>
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            <mi mathvariant="normal">N</mi>
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                <mn>3</mn>
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              <mo stretchy="false">)</mo>
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                <mn>6</mn>
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            </msub>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}}</annotation>
  </semantics></math></span></span></dd></dl><h2><span id=".E7.94.A8.E9.80.94"></span><span id="用途">用途</span></h2>
<p>六偏磷酸鈉是一種多價螯合劑並在工業中廣泛運用，包括作為食品添加劑。可以將碳酸鈉加入六偏磷酸鈉中，提高其pH值至8.0-8.6，作為硬水軟化劑和清潔劑使用。</p>
<h2><span id=".E5.8F.82.E8.A7.81"></span><span id="参见">參見</span></h2>
<ul><li>磷酸鈉</li>
<li>聚合物</li>
<li>螯合物</li></ul><h2><span id=".E5.8F.82.E8.80.83.E6.96.87.E7.8C.AE"></span><span id="参考文献">參考文獻</span></h2>
**六偏磷酸鈉**（英語：Sodium hexametaphosphate，縮寫：SHMP、E 編碼：E452 (i)），是指六聚體 (NaPO3)6。商品六偏磷酸鈉是多種聚磷酸鹽的混合物，即多偏磷酸鈉，而六聚物是其中的一種。

## 製備

1、磷酸二氫鈉法 由二水磷酸二氫鈉加熱至 110～230°C 分別脫去兩個結晶水和結構水，再進一步加熱至 620°C 脫水，生成偏磷酸鈉熔融物，並聚合成六偏磷酸鈉。然後卸出，從 650°C 冷卻至 60～80°C 時製片，經粉碎製得六偏磷酸鈉成品。

　
: ${\rm {\ NaH_{2}PO_{4}\cdot 2H_{2}O\rightarrow NaH_{2}PO_{4}+2H_{2}O}}$

　
: ${\rm {\ 2NaH_{2}PO_{4}\rightarrow Na_{2}H_{2}P_{2}O_{7}+H_{2}O}}$

　
: ${\rm {\ Na_{2}H_{2}P_{2}O_{7}\rightarrow 2NaPO_{3}+H_{2}O}}$

　
: ${\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}$

2、由五氧化二磷與純鹼按一定比例混合反應，並加熱使其脫聚，生成的六偏磷酸鈉熔體經驟冷製片、冷卻，得到工業六偏磷酸鈉成品。

　
: ${\rm {\ P_{2}O_{5}+Na_{2}CO_{3}\rightarrow 2NaPO_{3}+CO_{2}\uparrow }}$

　
: ${\rm {\ 6NaPO_{3}\rightarrow (NaPO_{3})_{6}}}$

## 用途

六偏磷酸鈉是一種多價螯合劑並在工業中廣泛運用，包括作為食品添加劑。可以將碳酸鈉加入六偏磷酸鈉中，提高其 pH 值至 8.0-8.6，作為硬水軟化劑和清潔劑使用。

## 參見

* 磷酸鈉
* 聚合物
* 螯合物

## 參考文獻
(NaPO3)6